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29556478
10.1007/s00029-016-0236-z
We study some aspects of modular generalized Springer theory for a complex reductive group $G$ with coefficients in a field $\mathbb k$ under the assumption that the characteristic $\ell$ of $\mathbb k$ is rather good for $G$, i.e., $\ell$ is good and does not divide the order of the component group of the centre of $G$. We prove a comparison theorem relating the characteristic-$\ell$ generalized Springer correspondence to the characteristic-$0$ version. We also consider Mautner's characteristic-$\ell$ `cleanness conjecture'; we prove it in some cases; and we deduce several consequences, including a classification of supercuspidal sheaves and an orthogonal decomposition of the equivariant derived category of the nilpotent cone.Comment: 26 page
Constructible sheaves on nilpotent cones in rather good characteristic
constructible sheaves on nilpotent cones in rather good characteristic
modular springer reductive mathbb mathbb i.e. divide relating springer correspondence version. mautner cleanness conjecture deduce consequences supercuspidal sheaves orthogonal decomposition equivariant nilpotent
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25063073
10.1007/s00029-016-0241-2
We introduce the Tesler polytope Tes_n(a_1,a_2,...,a_n), whose integer points are the Tesler matrices of size n with nonnegative integer hook sums a_1,a_2,...,a_n. We show that Tes_n(a) is a flow polytope and therefore the number of Tesler matrices is counted by the type A_n Kostant partition function evaluated at (a_1,a_2,...,a_n,-a_1-...-a_n). We describe the faces of this polytope in terms of "Tesler tableaux" and characterize when the polytope is simple. We prove that the h-vector of Tes_n(a) when all a_i>0 is given by the Mahonian numbers and calculate the volume of Tes_n(1,1,...,1) to be a product of consecutive Catalan numbers multiplied by the number of standard Young tableaux of staircase shape.Comment: 26 pages, 4 figures. v3 has a corrected proof of Lemma 2.4, updated reference
The polytope of Tesler matrices
the polytope of tesler matrices
tesler polytope integer tesler nonnegative integer hook sums polytope tesler counted kostant partition faces polytope tesler tableaux characterize polytope simple. mahonian consecutive catalan multiplied tableaux staircase pages figures. corrected updated
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42651291
10.1007/s00029-016-0259-5
Let $G$ be a $\mathbb{Q}_p$-split reductive group with connected centre and Borel subgroup $B=TN$. We construct a right exact functor $D^\vee_\Delta$ from the category of smooth modulo $p^n$ representations of $B$ to the category of projective limits of finitely generated \'etale $(\varphi,\Gamma)$-modules over a multivariable (indexed by the set of simple roots) commutative Laurent-series ring. These correspond to representations of a direct power of $\mathrm{Gal}(\overline{\mathbb{Q}_p}/\mathbb{Q}_p)$ via an equivalence of categories. Parabolic induction from a subgroup $P=L_PN_P$ corresponds to a basechange from a Laurent-series ring in those variables with corresponding simple roots contained in the Levi component $L_P$. $D^\vee_\Delta$ is exact and yields finitely generated objects on the category $SP_A$ of finite length representations with subquotients of principal series as Jordan-H\"older factors. Lifting the functor $D^\vee_\Delta$ to all (noncommuting) variables indexed by the positive roots allows us to construct a $G$-equivariant sheaf $\mathfrak{Y}_{\pi,\Delta}$ on $G/B$ and a $G$-equivariant continuous map from the Pontryagin dual $\pi^\vee$ of a smooth representation $\pi$ of $G$ to the global sections $\mathfrak{Y}_{\pi,\Delta}(G/B)$. We deduce that $D^\vee_\Delta$ is fully faithful on the full subcategory of $SP_A$ with Jordan-H\"older factors isomorphic to irreducible principal series.Comment: 55 pages, revised, to appear in Selecta Mathematic
Multivariable $(\varphi,\Gamma)$-modules and smooth $o$-torsion representations
multivariable $(\varphi,\gamma)$-modules and smooth $o$-torsion representations
mathbb split reductive borel subgroup functor delta modulo representations projective finitely etale varphi gamma modules multivariable indexed roots commutative laurent ring. representations mathrm overline mathbb mathbb equivalence categories. parabolic subgroup basechange laurent roots levi delta finitely representations subquotients principal jordan older factors. lifting functor delta noncommuting indexed roots equivariant sheaf mathfrak delta equivariant pontryagin mathfrak delta deduce delta faithful subcategory jordan older isomorphic irreducible principal pages revised selecta mathematic
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24997734
10.1007/s00029-016-0264-8
In 1998, Leclerc and Zelevinsky introduced the notion of weakly separated collections of subsets of the ordered $n$-element set $[n]$ (using this notion to give a combinatorial characterization for quasi-commuting minors of a quantum matrix). They conjectured the purity of certain natural domains $D\subseteq 2^{[n]}$ (in particular, of the hypercube $2^{[n]}$ itself, and the hyper-simplex $\{X\subseteq[n]\colon |X|=m\}$ for $m$ fixed), where $D$ is called pure if all maximal weakly separated collections in $D$ have the same cardinality. These conjectures have been answered affirmatively. In this paper, generalizing those earlier results, we reveal wider classes of pure domains in $2^{[n]}$. This is obtained as a consequence of our study of a novel geometric--combinatorial model for weakly separated set-systems, so-called \emph{combined (polygonal) tilings} on a zonogon, which yields a new insight in the area.Comment: 30 pages. Revised version. To appear in Selecta Mathematic
Combined tilings and separated set-systems
combined tilings and separated set-systems
leclerc zelevinsky notion weakly separated collections subsets ordered notion combinatorial quasi commuting minors conjectured purity subseteq hypercube hyper simplex subseteq colon maximal weakly separated collections cardinality. conjectures answered affirmatively. generalizing reveal wider geometric combinatorial weakly separated emph polygonal tilings zonogon insight pages. revised version. selecta mathematic
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25043340
10.1007/s00029-016-0266-6
We study a class of scalar, linear, non-local Riemann-Hilbert problems (RHP) involving finite subgroups of PSL(2,C). We associate to such problems a (maybe infinite) root system and describe the relevance of the orbits of the Weyl group in the construction of its solutions. As an application, we study in detail the large N expansion of SU(N) or SO(N) or Sp(2N) Chern-Simons partition function Z_N(M) of 3-manifolds M that are either rational homology spheres or more generally Seifert fibered spaces. It has a matrix model-like representation, whose spectral curve can be characterized in terms of a RHP as above. When pi_1(M) is finite (i.e. for manifolds M that are quotients of \mathbb{S}_{3} by a finite isometry group of type ADE), the Weyl group associated to the RHP is finite and the spectral curve is algebraic and can be in principle computed. We then show that the large $N$ expansion of Z_N(M) is computed by the topological recursion. This has consequences for the analyticity properties of SU/SO/Sp perturbative invariants of knots along fibers in $M$.Comment: 92 pages, 20 figures. Section 9 by Alexander Wei{\ss}
Root systems, spectral curves, and analysis of a Chern-Simons matrix model for Seifert fibered spaces
root systems, spectral curves, and analysis of a chern-simons matrix model for seifert fibered spaces
riemann hilbert involving subgroups associate maybe infinite relevance orbits weyl solutions. chern simons partition manifolds rational homology spheres seifert fibered spaces. above. i.e. manifolds quotients mathbb isometry weyl algebraic computed. topological recursion. consequences analyticity perturbative invariants knots fibers .comment pages figures. alexander
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42673693
10.1007/s00029-016-0280-8
We prove that the dg category of perfect complexes on a smooth, proper Deligne-Mumford stack over a field of characteristic zero is geometric in the sense of Orlov, and in particular smooth and proper. On the level of triangulated categories, this means that the derived category of perfect complexes embeds as an admissible subcategory into the bounded derived category of coherent sheaves on a smooth, projective variety. The same holds for a smooth, projective, tame Artin stack over an arbitrary field.Comment: 31 page
Geometricity for derived categories of algebraic stacks
geometricity for derived categories of algebraic stacks
perfect complexes proper deligne mumford stack geometric orlov proper. triangulated categories perfect complexes embeds admissible subcategory coherent sheaves projective variety. projective tame artin stack
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29534677
10.1007/s00029-016-0285-3
Schwartz functions, or measures, are defined on any smooth semi-algebraic ("Nash") manifold, and are known to form a cosheaf for the semi-algebraic restricted topology. We extend this definition to smooth semi-algebraic stacks, which are defined as geometric stacks in the category of Nash manifolds. Moreover, when those are obtained from algebraic quotient stacks of the form X/G, with X a smooth affine variety and G a reductive group defined over a global field k, we define, whenever possible, an "evaluation map" at each semisimple k-point of the stack, without using truncation methods. This corresponds to a regularization of the sum of those orbital integrals whose semisimple part corresponds to the chosen k-point. These evaluation maps produce, in principle, a distribution which generalizes the Arthur-Selberg trace formula and Jacquet's relative trace formula, although the former, and many instances of the latter, cannot actually be defined by the purely geometric methods of this paper. In any case, the stack-theoretic point of view provides an explanation for the pure inner forms that appear in many versions of the Langlands, and relative Langlands, conjectures.Comment: 96pp. Erratum added at the end to fix two gaps and strengthen some statements from quasi-isomorphism to homotopy equivalenc
The Schwartz space of a smooth semi-algebraic stack
the schwartz space of a smooth semi-algebraic stack
schwartz algebraic nash manifold cosheaf algebraic restricted topology. extend algebraic stacks geometric stacks nash manifolds. algebraic quotient stacks affine reductive whenever semisimple stack truncation methods. regularization orbital integrals semisimple point. generalizes arthur selberg trace jacquet trace former instances purely geometric paper. stack theoretic explanation versions langlands langlands erratum gaps strengthen statements quasi isomorphism homotopy equivalenc
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29529746
10.1007/s00029-016-0287-1
We study a moduli problem on a nodal curve of arithmetic genus 1, whose solution is an open subscheme in the zastava space for projective line. This moduli space is equipped with a natural Poisson structure, and we compute it in a natural coordinate system. We compare this Poisson structure with the trigonometric Poisson structure on the transversal slices in an affine flag variety. We conjecture that certain generalized minors give rise to a cluster structure on the trigonometric zastava.Comment: Main text by M. Finkelberg, A. Kuznetsov and L. Rybnikov with an appendix by G. Dobrovolska; v3 32 pages, Proof of Proposition 4.3 corrected, Section 1.5 added; v4 33 pages, the final version to appear in Selecta Math.; v5 the published versio
Towards a cluster structure on trigonometric zastava
towards a cluster structure on trigonometric zastava
moduli nodal arithmetic genus subscheme zastava projective line. moduli equipped poisson coordinate system. poisson trigonometric poisson transversal slices affine flag variety. conjecture minors trigonometric finkelberg kuznetsov rybnikov dobrovolska pages corrected pages selecta math. versio
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29524841
10.1007/s00029-016-0290-6
For a left coherent ring A with every left ideal having a countable set of generators, we show that the coderived category of left A-modules is compactly generated by the bounded derived category of finitely presented left A-modules (reproducing a particular case of a recent result of Stovicek with our methods). Furthermore, we present the definition of a dualizing complex of fp-injective modules over a pair of noncommutative coherent rings A and B, and construct an equivalence between the coderived category of A-modules and the contraderived category of B-modules. Finally, we define the notion of a relative dualizing complex of bimodules for a pair of noncommutative ring homomorphisms A \to R and B \to S, and obtain an equivalence between the R/A-semicoderived category of R-modules and the S/B-semicontraderived category of S-modules. For a homomorphism of commutative rings A\to R, we also construct a tensor structure on the R/A-semicoderived category of R-modules. A vision of semi-infinite algebraic geometry is discussed in the introduction.Comment: LaTeX 2e with pb-diagram and xy-pic, 30 pages, 2 commutative diagrams; v.3: several misprints corrected, expositional improvement in Section 2; v.4: examples added in the introduction and in Sections 3 and 5; v.5: more misprints corrected, new Section 6 added; v.6: exposition improved in Section 6 -- this is intended as the final versio
Coherent rings, fp-injective modules, dualizing complexes, and covariant Serre-Grothendieck duality
coherent rings, fp-injective modules, dualizing complexes, and covariant serre-grothendieck duality
coherent ideal countable generators coderived modules compactly finitely modules reproducing stovicek dualizing injective modules noncommutative coherent rings equivalence coderived modules contraderived modules. notion dualizing bimodules noncommutative homomorphisms equivalence semicoderived modules semicontraderived modules. homomorphism commutative rings semicoderived modules. vision infinite algebraic latex pages commutative diagrams misprints corrected expositional misprints corrected exposition intended versio
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42680592
10.1007/s00029-016-0293-3
We study Quot schemes of 0-dimensional quotients of sheaves on 3-folds $X$. When the sheaf $\mathcal{R}$ is rank 2 and reflexive, we prove that the generating function of Euler characteristics of these Quot schemes is a power of the MacMahon function times a polynomial. This polynomial is itself the generating function of Euler characteristics of Quot schemes of a certain 0-dimensional sheaf, which is supported on the locus where $\mathcal{R}$ is not locally free. In the case $X = \mathbb{C}^3$ and $\mathcal{R}$ is equivariant, we use our result to prove an explicit product formula for the generating function. This formula was first found using localization techniques in previous joint work with B. Young. Our results follow from R. Hartshorne's Serre correspondence and a rank 2 version of a Hall algebra calculation by J. Stoppa and R.P. Thomas.Comment: 20 pages. Published version. Addition to published version: the assumptions in Thm. 1.2 can be weakened due to an argument from J. Rennemo (Section 1.2
Rank 2 wall-crossing and the Serre correspondence
rank 2 wall-crossing and the serre correspondence
quot schemes quotients sheaves folds sheaf mathcal reflexive generating euler quot schemes macmahon polynomial. generating euler quot schemes sheaf locus mathcal locally free. mathbb mathcal equivariant generating function. localization young. hartshorne serre correspondence hall stoppa r.p. pages. version. assumptions thm. weakened argument rennemo
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42676587
10.1007/s00029-016-0295-1
In this paper, we continue the study of the existence problem of compact Clifford-Klein forms from a cohomological point of view, which was initiated by Kobayashi-Ono and extended by Benoist-Labourie and the author. We give an obstruction to the existence of compact Clifford-Klein forms by relating a natural homomorphism from relative Lie algebra cohomology to de Rham cohomology with an upper-bound estimate for cohomological dimensions of discontinuous groups. From this obstruction, we derive some examples, e.g. $\mathrm{SO}_0(p+r, q)/(\mathrm{SO}_0(p,q) \times \mathrm{SO}(r))$ $(p,q,r \geq 1, \ q:\text{odd})$ and $\mathrm{SL}(p+q, \mathbb{C})/\mathrm{SU}(p,q)$ $(p,q \geq 1)$, of a homogeneous space that does not admit a compact Clifford-Klein form. To construct these examples, we apply H. Cartan's theorem on relative Lie algebra cohomology of reductive pairs and the theory of $\epsilon$-families of semisimple symmetric pairs.Comment: 18 page
A cohomological obstruction to the existence of compact Clifford-Klein forms
a cohomological obstruction to the existence of compact clifford-klein forms
continue clifford klein cohomological initiated kobayashi benoist labourie author. obstruction clifford klein relating homomorphism cohomology rham cohomology cohomological discontinuous groups. obstruction derive e.g. mathrm mathrm mathrm mathrm mathbb mathrm homogeneous admit clifford klein form. cartan cohomology reductive epsilon families semisimple
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42680112
10.1007/s00029-016-0296-0
We prove that a universal class categorical in a high-enough cardinal is categorical on a tail of cardinals. As opposed to other results in the literature, we work in ZFC, do not require the categoricity cardinal to be a successor, do not assume amalgamation, and do not use large cardinals. Moreover we give an explicit bound on the "high-enough" threshold: $\mathbf{Theorem}$ Let $\psi$ be a universal $\mathbb{L}_{\omega_1, \omega}$ sentence. If $\psi$ is categorical in some $\lambda \ge \beth_{\beth_{\omega_1}}$, then $\psi$ is categorical in all $\lambda' \ge \beth_{\beth_{\omega_1}}$. As a byproduct of the proof, we show that a conjecture of Grossberg holds in universal classes: $\mathbf{Corollary}$ Let $\psi$ be a universal $\mathbb{L}_{\omega_1, \omega}$ sentence that is categorical in some $\lambda \ge \beth_{\beth_{\omega_1}}$, then the class of models of $\psi$ has the amalgamation property for models of size at least $\beth_{\beth_{\omega_1}}$. We also establish generalizations of these two results to uncountable languages. As part of the argument, we develop machinery to transfer model-theoretic properties between two different classes satisfying a compatibility condition. This is used as a bridge between Shelah's milestone study of universal classes (which we use extensively) and a categoricity transfer theorem of the author for abstract elementary classes that have amalgamation, are tame, and have primes over sets of the form $M \cup \{a\}$.Comment: 49 page
Shelah's eventual categoricity conjecture in universal classes. Part II
shelah's eventual categoricity conjecture in universal classes. part ii
universal categorical cardinal categorical tail cardinals. opposed categoricity cardinal successor amalgamation cardinals. mathbf universal mathbb omega omega sentence. categorical lambda beth beth omega categorical lambda beth beth omega byproduct conjecture grossberg universal mathbf corollary universal mathbb omega omega sentence categorical lambda beth beth omega amalgamation beth beth omega establish generalizations uncountable languages. argument machinery theoretic satisfying compatibility condition. bridge shelah milestone universal extensively categoricity elementary amalgamation tame primes .comment
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42691950
10.1007/s00029-017-0302-1
The topological vertex is a universal series which can be regarded as an object in combinatorics, representation theory, geometry, or physics. It encodes the combinatorics of 3D partitions, the action of vertex operators on Fock space, the Donaldson-Thomas theory of toric Calabi-Yau threefolds, or the open string partition function of $\mathbb{C}^3$. We prove several identities in which a sum over terms involving the topological vertex is expressed as a closed formula, often a product of simple terms, closely related to Fourier expansions of Jacobi forms. We use purely combinatorial and representation theoretic methods to prove our formulas, but we discuss applications to the Donaldson-Thomas invariants of elliptically fibered Calabi-Yau threefolds at the end of the paper.Comment: 21 page
Trace Identities for the Topological Vertex
trace identities for the topological vertex
topological universal regarded combinatorics physics. encodes combinatorics partitions fock donaldson thomas toric calabi threefolds partition mathbb identities involving topological closely fourier expansions jacobi forms. purely combinatorial theoretic formulas donaldson thomas invariants elliptically fibered calabi threefolds
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29501489
10.1007/s00029-017-0314-x
We call a knot in the 3-sphere $SU(2)$-simple if all representations of the fundamental group of its complement which map a meridian to a trace-free element in $SU(2)$ are binary dihedral. This is a generalisation of being a 2-bridge knot. Pretzel knots with bridge number $\geq 3$ are not $SU(2)$-simple. We provide an infinite family of knots $K$ with bridge number $\geq 3$ which are $SU(2)$-simple. One expects the instanton knot Floer homology $I^\natural(K)$ of a $SU(2)$-simple knot to be as small as it can be -- of rank equal to the knot determinant $\det(K)$. In fact, the complex underlying $I^\natural(K)$ is of rank equal to $\det(K)$, provided a genericity assumption holds that is reasonable to expect. Thus formally there is a resemblance to strong L-spaces in Heegaard Floer homology. For the class of $SU(2)$-simple knots that we introduce this formal resemblance is reflected topologically: The branched double covers of these knots are strong L-spaces. In fact, somewhat surprisingly, these knots are alternating. However, the Conway spheres are hidden in any alternating diagram. With the methods we use, we show that an integer homology 3-sphere which is a graph manifold always admits irreducible representations of its fundamental group.Comment: 22 pages, 10 figures, to appear in Selecta Mathematic
A class of knots with simple $SU(2)$ representations
a class of knots with simple $su(2)$ representations
call knot sphere representations complement meridian trace dihedral. generalisation bridge knot. pretzel knots bridge simple. infinite knots bridge simple. expects instanton knot floer homology knot knot determinant genericity reasonable expect. formally resemblance heegaard floer homology. knots formal resemblance reflected topologically branched covers knots spaces. somewhat surprisingly knots alternating. conway spheres hidden alternating diagram. integer homology sphere manifold admits irreducible representations pages selecta mathematic
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42735742
10.1007/s00029-017-0315-9
Let $\mathfrak{g}$ be a simple finite-dimensional Lie superalgebra with a non-degenerate supersymmetric even invariant bilinear form, $f$ a nilpotent element in the even part of $\mathfrak{g}$, $\Gamma$ a good grading of $\mathfrak{g}$ for $f$ and $\mathcal{W}^{k}(\mathfrak{g},f;\Gamma)$ the $\mathcal{W}$-algebra associated with $\mathfrak{g},f,k,\Gamma$ defined by the generalized Drinfeld-Sokolov reduction. In this paper, we present each $\mathcal{W}$-algebra as the intersection of kernels of the screening operators, acting on the tensor vertex superalgebra of an affine vertex superalgebra and a neutral free superfermion vertex superalgebra. As applications, we prove that the $\mathcal{W}$-algebra associated with a regular nilpotent element in $\mathfrak{osp}(1,2n)$ is isomorphic to the $\mathcal{W}B_{n}$-algebra introduced by Fateev and Lukyanov, and that the $\mathcal{W}$-algebra associated with a subregular nilpotent element in $\mathfrak{sl}_{n}$ is isomorphic to the $\mathcal{W}^{(2)}_{n}$-algebra introduced by Feigin and Semikhatov.Comment: revised version, to appear in Sel. Math. New Se
Screening operators for W-algebras
screening operators for w-algebras
mathfrak superalgebra degenerate supersymmetric bilinear nilpotent mathfrak gamma grading mathfrak mathcal mathfrak gamma mathcal mathfrak gamma drinfeld sokolov reduction. mathcal intersection kernels screening acting superalgebra affine superalgebra neutral superfermion superalgebra. mathcal nilpotent mathfrak isomorphic mathcal fateev lukyanov mathcal subregular nilpotent mathfrak isomorphic mathcal feigin revised sel. math.
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42751172
10.1007/s00029-017-0316-8
The goal of this work is to provide an elementary construction of the canonical basis $\mathbf B(w)$ in each quantum Schubert cell~$U_q(w)$ and to establish its invariance under modified Lusztig's symmetries. To that effect, we obtain a direct characterization of the upper global basis $\mathbf B^{up}$ in terms of a suitable bilinear form and show that $\mathbf B(w)$ is contained in $\mathbf B^{up}$ and its large part is preserved by modified Lusztig's symmetries.Comment: AMSLaTeX, 32 pages,typos correcte
Canonical bases of quantum Schubert cells and their symmetries
canonical bases of quantum schubert cells and their symmetries
goal elementary canonical mathbf schubert establish invariance lusztig symmetries. mathbf bilinear mathbf mathbf preserved lusztig amslatex pages typos correcte
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42744748
10.1007/s00029-017-0319-5
We look at Poisson geometry taking the viewpoint of singular foliations, understood as suitable submodules generated by Hamiltonian vector fields rather than partitions into (symplectic) leaves. The class of Poisson structures which behave best from this point of view, are those whose submodule generated by Hamiltonian vector fields arises from a smooth holonomy groupoid. We call them almost regular Poisson structures and determine them completely. They include regular Poisson and log symplectic manifolds, as well as several other Poisson structures whose symplectic foliation presents singularities. We show that the holonomy groupoid associated with an almost regular Poisson structure is a Poisson groupoid, integrating a naturally associated Lie bialgebroid. The Poisson structure on the holonomy groupoid is regular, and as such it provides a desingularization. The holonomy groupoid is "minimal" among Lie groupoids which give rise to the submodule generated by Hamiltonian vector fields. This implies that, in the case of log-symplectic manifolds, the holonomy groupoid coincides with the symplectic groupoid constructed by Gualtieri and Li. Last, we focus on the integrability of almost regular Poisson manifolds and exhibit the role of the second homotopy group of the source-fibers of the holonomy groupoid.Comment: 36 pages. This version has been accepted for publicatio
Almost regular Poisson manifolds and their holonomy groupoids
almost regular poisson manifolds and their holonomy groupoids
look poisson viewpoint singular foliations understood submodules partitions symplectic leaves. poisson behave submodule arises holonomy groupoid. call poisson completely. poisson symplectic manifolds poisson symplectic foliation presents singularities. holonomy groupoid poisson poisson groupoid integrating naturally bialgebroid. poisson holonomy groupoid desingularization. holonomy groupoid groupoids submodule fields. symplectic manifolds holonomy groupoid coincides symplectic groupoid gualtieri integrability poisson manifolds exhibit homotopy fibers holonomy pages. publicatio
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29528919
10.1007/s00029-017-0324-8
We present a new method of proving the Diophantine extremality of various dynamically defined measures, vastly expanding the class of measures known to be extremal. This generalizes and improves the celebrated theorem of Kleinbock and Margulis ('98) resolving Sprind\v{z}uk's conjecture, as well as its extension by Kleinbock, Lindenstrauss, and Weiss ('04), hereafter abbreviated KLW. As applications we prove the extremality of all hyperbolic measures of smooth dynamical systems with sufficiently large Hausdorff dimension, and of the Patterson--Sullivan measures of all nonplanar geometrically finite groups. The key technical idea, which has led to a plethora of new applications, is a significant weakening of KLW's sufficient conditions for extremality. In Part I, we introduce and develop a systematic account of two classes of measures, which we call $quasi$-$decaying$ and $weakly$ $quasi$-$decaying$. We prove that weak quasi-decay implies strong extremality in the matrix approximation framework (which has received much attention in recent years), thus proving a conjecture of KLW. We also prove the "inherited exponent of irrationality" version of this theorem, describing the relationship between the Diophantine properties of certain subspaces of the space of matrices and measures supported on these subspaces. In subsequent papers, we exhibit numerous examples of quasi-decaying measures, in support of the thesis that "almost any measure from dynamics and/or fractal geometry is quasi-decaying". In addition to the examples described above, we also prove (for example) that Gibbs measures (including conformal measures) of infinite iterated function systems are quasi-decaying, even if the systems in question do not satisfy the open set condition. We also discuss examples of non-extremal measures coming from dynamics, illustrating where the theory must halt.Comment: Link to part II: arXiv:1508.0559
Extremality and dynamically defined measures, part I: Diophantine properties of quasi-decaying measures
extremality and dynamically defined measures, part i: diophantine properties of quasi-decaying measures
proving diophantine extremality dynamically vastly expanding extremal. generalizes improves celebrated kleinbock margulis resolving sprind conjecture kleinbock lindenstrauss weiss hereafter abbreviated klw. extremality hyperbolic sufficiently hausdorff patterson sullivan nonplanar geometrically groups. plethora weakening extremality. call quasi decaying weakly quasi decaying quasi extremality proving conjecture klw. inherited exponent irrationality describing diophantine subspaces subspaces. papers exhibit numerous quasi decaying thesis fractal quasi decaying gibbs conformal infinite iterated quasi decaying satisfy condition. extremal coming illustrating
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73388729
10.1007/s00029-017-0328-4
We refine the statement of the denominator and evaluation conjectures for affine Macdonald polynomials proposed by Etingof-Kirillov Jr. and prove the first non-trivial cases of these conjectures. Our results provide a q-deformation of the computation of genus 1 conformal blocks via elliptic Selberg integrals by Felder-Stevens-Varchenko. They allow us to give precise formulations for the affine Macdonald conjectures in the general case which are consistent with computer computations. Our method applies recent work of the second named author to relate these conjectures in the case of $U_q(\widehat{\mathfrak{sl}}_2)$ to evaluations of certain theta hypergeometric integrals defined by Felder-Varchenko. We then evaluate the resulting integrals, which may be of independent interest, by well-chosen applications of the elliptic beta integral introduced by Spiridonov.Comment: 26 pages. v3: minor edits for published versio
Affine Macdonald conjectures and special values of Felder-Varchenko functions
affine macdonald conjectures and special values of felder-varchenko functions
refine statement denominator conjectures affine macdonald polynomials etingof kirillov trivial conjectures. deformation genus conformal blocks elliptic selberg integrals felder stevens varchenko. precise formulations affine macdonald conjectures computations. applies named relate conjectures widehat mathfrak evaluations theta hypergeometric integrals felder varchenko. integrals elliptic beta pages. minor edits versio
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42678862
10.1007/s00029-017-0338-2
We prove an inequality between the $L^{\infty}$-norm of the contact Hamiltonian of a positive loop of contactomorphims and the minimal Reeb period. This implies that there are no small positive loops on hypertight or Liouville fillable contact manifolds. Non-existence of small positive loops for overtwisted 3-manifolds was proved by Casals-Presas-Sandon in [CPS16]. As corollaries of the inequality we deduce various results. E.g. we prove that certain periodic Reeb flows are the unique minimizers of the $L^\infty$-norm. Moreover, we establish $L^\infty$-type contact systolic inequalities in the presence of a positive loop.Comment: 26 pages, 6 figures; v2: corrected an error, changed statements of main theorems; v3: accepted version, to appear in Selecta Mathematic
Positive loops and $L^{\infty}$-contact systolic inequalities
positive loops and $l^{\infty}$-contact systolic inequalities
inequality infty norm contactomorphims reeb period. loops hypertight liouville fillable manifolds. loops overtwisted manifolds proved casals presas sandon corollaries inequality deduce results. e.g. reeb flows minimizers infty norm. establish infty systolic inequalities pages corrected changed statements theorems selecta mathematic
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42664337
10.1007/s00029-017-0339-1
We provide a construction of free factorization algebras in algebraic geometry and link factorization homology of a scheme with coefficients in a free factorization algebra to the homology of its (unordered) configuration spaces. As an application, this construction allows for a purely algebro-geometric proof of homological stability of configuration spaces.Comment: The final publication is available at Springer via http://dx.doi.org/doi:10.1007/s00029-017-0339-1, Selecta Mathematica (N.S.) 201
Free factorization algebras and homology of configuration spaces in algebraic geometry
free factorization algebras and homology of configuration spaces in algebraic geometry
factorization algebras algebraic factorization homology factorization homology unordered spaces. purely algebro geometric homological publication springer selecta mathematica n.s.
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42667549
10.1007/s00029-017-0343-5
We explore the relationship between a certain "abelian duality" property of spaces and the propagation properties of their cohomology jump loci. To that end, we develop the analogy between abelian duality spaces and those spaces which possess what we call the "EPY property." The same underlying homological algebra allows us to deduce the propagation of jump loci: in the former case, characteristic varieties propagate, and in the latter, the resonance varieties. We apply the general theory to arrangements of linear and elliptic hyperplanes, as well as toric complexes, right-angled Artin groups, and Bestvina-Brady groups. Our approach brings to the fore the relevance of the Cohen-Macaulay condition in this combinatorial context.Comment: 30 page
Abelian duality and propagation of resonance
abelian duality and propagation of resonance
explore abelian duality propagation cohomology jump loci. analogy abelian duality possess call property. homological deduce propagation jump loci former varieties propagate varieties. arrangements elliptic hyperplanes toric complexes angled artin bestvina brady groups. brings fore relevance cohen macaulay combinatorial
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73958233
10.1007/s00029-017-0344-4
We discuss a conjecture saying that derived equivalence of simply connected smooth projective varieties implies that the difference of their classes in the Grothendieck ring of varieties is annihilated by a power of the affine line class. We support the conjecture with a number of known examples, and one new example. We consider a smooth complete intersection $X$ of three quadrics in ${\mathbf P}^5$ and the corresponding double cover $Y \to {\mathbf P}^2$ branched over a sextic curve. We show that as soon as the natural Brauer class on $Y$ vanishes, so that $X$ and $Y$ are derived equivalent, the difference $[X] - [Y]$ is annihilated by the affine line class.Comment: Exposition improved, main conjecture slightly update
Grothendieck ring of varieties, D- and L-equivalence, and families of quadrics
grothendieck ring of varieties, d- and l-equivalence, and families of quadrics
conjecture saying equivalence projective varieties grothendieck varieties annihilated affine class. conjecture example. intersection quadrics mathbf cover mathbf branched sextic curve. soon brauer vanishes annihilated affine exposition conjecture update
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42698211
10.1007/s00029-017-0348-0
We study graded nonlocal $\underline{\mathsf{q}}$-vertex algebras and we prove that they can be generated by certain sets of vertex operators. As an application, we consider the family of graded nonlocal $\underline{\mathsf{q}}$-vertex algebras $V_{c,1}$, $c\geq 1$, associated with the principal subspaces $W(c\Lambda_0)$ of the integrable highest weight $U_q (\hat{\mathfrak{sl}}_2)$-modules $L(c\Lambda_0)$. Using quantum integrability, we derive combinatorial bases for $V_{c,1}$ and compute the corresponding character formulae.Comment: 28 pages, 1 figur
Higher level vertex operators for $U_q (\hat{\mathfrak{sl}}_2)$
higher level vertex operators for $u_q (\hat{\mathfrak{sl}}_2)$
graded nonlocal underline mathsf algebras operators. graded nonlocal underline mathsf algebras principal subspaces lambda integrable mathfrak modules lambda integrability derive combinatorial bases character pages figur
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111364709
10.1007/s00029-017-0349-z
In this paper we study higher Deligne–Lusztig representations of reductive\ud groups over finite quotients of discrete valuation rings. At even levels, we show that\ud these geometrically constructed representations, defined by Lusztig, coincide with\ud certain explicit induced representations defined by Gérardin, thus giving a solution\ud to a problem raised by Lusztig. In particular, we determine the dimensions of these\ud representations. As an immediate application we verify a conjecture of Letellier for\ud GL2 and GL3
The algebraisation of higher Deligne–Lusztig representations.
the algebraisation of higher deligne–lusztig representations.
deligne–lusztig representations reductive quotients valuation rings. geometrically representations lusztig coincide representations gérardin giving raised lusztig. representations. immediate verify conjecture letellier
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73404603
10.1007/s00029-017-0381-z
Let k be a field of characteristic zero. Etingof and Kazhdan constructed a quantisation U_h(b) of any Lie bialgebra b over k, which depends on the choice of an associator Phi. They prove moreover that this quantisation is functorial in b. Remarkably, the quantum group U_h(b) is endowed with a Tannakian equivalence F_b from the braided tensor category of Drinfeld-Yetter modules over b, with deformed associativity constraints given by Phi, to that of Drinfeld-Yetter modules over U_h(b). In this paper, we prove that the equivalence F_b is functorial in b.Comment: Small revisions in Sections 2 and 6. An appendix added on the equivalence between admissible Drinfeld-Yetter modules over a QUE and modules over its quantum double. To appear in Selecta Math. 71 page
A 2-categorical extension of Etingof-Kazhdan quantisation
a 2-categorical extension of etingof-kazhdan quantisation
zero. etingof kazhdan quantisation bialgebra associator phi. quantisation functorial remarkably endowed tannakian equivalence braided drinfeld yetter modules deformed associativity drinfeld yetter modules equivalence functorial revisions equivalence admissible drinfeld yetter modules modules double. selecta math.
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29499170
10.1007/s00029-017-0383-x
We present a theory of the $b$-function (or Bernstein-Sato polynomial) in positive characteristic. Let $f$ be a non-constant polynomial with coefficients in a perfect field $k$ of characteristic $p>0.$ Its $b$-function $b_f$ is defined to be an ideal of the algebra of continuous $k$-valued functions on $\mathbb{Z}_p.$ The zero-locus of the $b$-function is thus naturally interpreted as a subset of $\mathbb{Z}_p,$ which we call the set of roots of $b_f.$ We prove that $b_f$ has finitely many roots and that they are negative rational numbers. Our construction builds on an earlier work of Musta\c{t}\u{a} and is in terms of $D$-modules, where $D$ is the ring of Grothendieck differential operators. We use the Frobenius to obtain finiteness properties of $b_f$ and relate it to the test ideals of $f.$Comment: Final versio
On a theory of the $b$-function in positive characteristic
on a theory of the $b$-function in positive characteristic
bernstein sato characteristic. perfect ideal valued mathbb locus naturally interpreted mathbb call roots finitely roots rational numbers. builds musta modules grothendieck operators. frobenius finiteness relate ideals comment versio
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42641883
10.1007/s00029-017-0384-9
We study the relative orbifold Donaldson-Thomas theory of $[\mathbb{C}^2/\mathbb{Z}_{n+1}]\times \mathbb{P}^1$. We establish a correspondence between the DT theory relative to 3 fibers to quantum multiplication by divisors in the Hilbert scheme of points on $[\mathbb{C}^2/\mathbb{Z}_{n+1}]$. This determines the whole theory if a further nondegeneracy condition is assumed. The result can also be viewed as a crepant resolution correspondence to the DT theory of $\mathcal{A}_n\times \mathbb{P}^1$.Comment: 44 pages, 1 figure. Minor changes, Selecta Mathematica New Series (2018
Donaldson-Thomas theory of $[\mathbb{C}^2/\mathbb{Z}_{n+1}]\times \mathbb{P}^1$
donaldson-thomas theory of $[\mathbb{c}^2/\mathbb{z}_{n+1}]\times \mathbb{p}^1$
orbifold donaldson thomas mathbb mathbb mathbb establish correspondence fibers multiplication divisors hilbert mathbb mathbb determines nondegeneracy assumed. viewed crepant correspondence mathcal mathbb .comment pages figure. minor selecta mathematica
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73408994
10.1007/s00029-017-0387-6
The Littlewood--Richardson process is a discrete random point process arising from the isotypic decomposition of tensor products of irreducible representations of $\operatorname{GL}_N(\mathbb{C})$. Biane--Perelomov--Popov matrices are quantum random matrices obtained as the geometric quantization of random Hermitian matrices with deterministic eigenvalues and uniformly random eigenvectors. As first observed by Biane, correlation functions of certain global observables of the LR process coincide with correlation functions of linear statistics of sums of classically independent BPP matrices, thereby enabling a random matrix approach to the statistical study of $\operatorname{GL}_N(\mathbb{C})$ tensor products. In this paper, we prove an optimal result: classically independent BPP matrices become freely independent in any semiclassical/large-dimension limit. This proves and generalizes a conjecture of Bufetov and Gorin, and leads to a Law of Large Numbers for the BPP observables of the LR process which holds in any and all semiclassical scalings.Comment: 52 page
Semiclassical asymptotics of $\operatorname{GL}_N(\mathbb{C})$ tensor products and quantum random matrices
semiclassical asymptotics of $\operatorname{gl}_n(\mathbb{c})$ tensor products and quantum random matrices
littlewood richardson arising isotypic decomposition irreducible representations operatorname mathbb biane perelomov popov geometric quantization hermitian deterministic eigenvalues uniformly eigenvectors. biane observables coincide sums classically thereby enabling operatorname mathbb products. classically freely semiclassical limit. proves generalizes conjecture bufetov gorin observables semiclassical
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42668626
10.1007/s00029-018-0389-z
We study plane partitions satisfying condition $a_{n+1,m+1}=0$ (this condition is called "pit") and asymptotic conditions along three coordinate axes. We find the formulas for generating function of such plane partitions. Such plane partitions label the basis vectors in certain representations of quantum toroidal $\mathfrak{gl}_1$ algebra, therefore our formulas can be interpreted as the characters of these representations. The resulting formulas resemble formulas for characters of tensor representations of Lie superalgebra $\mathfrak{gl}_{m|n}$. We discuss representation theoretic interpretation of our formulas using $q$-deformed $W$-algebra $\mathfrak{gl}_{m|n}$.Comment: 30 pages, v2. 32 pages, new subsection 4.4 included, v3 36 pages, many corrections, references added, v4 38 pages many corrections, references added, version to appear in Sel. Math. New Ser. (2018
Plane partitions with a "pit": generating functions and representation theory
plane partitions with a "pit": generating functions and representation theory
partitions satisfying asymptotic coordinate axes. formulas generating partitions. partitions label representations toroidal mathfrak formulas interpreted characters representations. formulas resemble formulas characters representations superalgebra mathfrak theoretic formulas deformed mathfrak .comment pages pages subsection pages pages sel. math. ser.
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73956427
10.1007/s00029-018-0394-2
Following the proof of the purity conjecture for weakly separated collections, recent years have revealed a variety of wider examples of purity in different settings. In this paper we consider the collection $\mathcal A_{I,J}$ of sets that are weakly separated from two fixed sets $I$ and $J$. We show that all maximal by inclusion weakly separated collections $\mathcal W\subset\mathcal A_{I,J}$ are also maximal by size, provided that $I$ and $J$ are sufficiently "generic". We also give a simple formula for the cardinality of $\mathcal W$ in terms of $I$ and $J$. We apply our result to calculate the cluster distance and to give lower bounds on the mutation distance between cluster variables in the cluster algebra structure on the coordinate ring of the Grassmannian. Using a linear projection that relates weak separation to the octahedron recurrence, we also find the exact mutation distances and cluster distances for a family of cluster variables.Comment: 44 pages, 11 figure
Weak Separation, Pure Domains and Cluster Distance
weak separation, pure domains and cluster distance
purity conjecture weakly separated collections wider purity settings. mathcal weakly separated maximal inclusion weakly separated collections mathcal mathcal maximal sufficiently generic cardinality mathcal bounds mutation coordinate grassmannian. projection relates octahedron recurrence mutation distances distances pages
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73959871
10.1007/s00029-018-0405-3
In this paper, we study the geometry of various Hessenberg varieties in type A, as well as families thereof, with the additional goal of laying the groundwork for future computations of Newton-Okounkov bodies of Hessenberg varieties. Our main results are as follows. We find explicit and computationally convenient generators for the local defining ideals of indecomposable regular nilpotent Hessenberg varieties, and then show that all regular nilpotent Hessenberg varieties are local complete intersections. We also show that certain families of Hessenberg varieties, whose generic fibers are regular semisimple Hessenberg varieties and the special fiber is a regular nilpotent Hessenberg variety, are flat and have reduced fibres. This result further allows us to give a computationally effective formula for the degree of a regular nilpotent Hessenberg variety with respect to a Pl\"ucker embedding. Furthermore, we construct certain flags of subvarieties of a regular nilpotent Hessenberg variety, obtained by intersecting with Schubert varieties, which are suitable for computing Newton-Okounkov bodies. As an application of our results, we explicitly compute many Newton-Okounkov bodies of the two-dimensional Peterson variety with respect to Pl\"ucker embeddings.Comment: 25 pages. Arguments substantially streamlined thanks to comments from anonymous referee. Readers who want more leisurely explanations may wish to consult our first version on the ArXi
Geometry of Hessenberg varieties with applications to Newton-Okounkov bodies
geometry of hessenberg varieties with applications to newton-okounkov bodies
hessenberg varieties families thereof goal laying groundwork computations newton okounkov bodies hessenberg varieties. follows. computationally convenient generators defining ideals indecomposable nilpotent hessenberg varieties nilpotent hessenberg varieties intersections. families hessenberg varieties generic fibers semisimple hessenberg varieties fiber nilpotent hessenberg fibres. computationally nilpotent hessenberg ucker embedding. flags subvarieties nilpotent hessenberg intersecting schubert varieties newton okounkov bodies. explicitly newton okounkov bodies peterson ucker pages. arguments substantially streamlined thanks comments anonymous referee. readers want leisurely explanations wish consult arxi
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73350291
10.1007/s00029-018-0406-2
We define and study coisotropic structures on morphisms of commutative dg algebras in the context of shifted Poisson geometry, i.e. $P_n$-algebras. Roughly speaking, a coisotropic morphism is given by a $P_{n+1}$-algebra acting on a $P_n$-algebra. One of our main results is an identification of the space of such coisotropic structures with the space of Maurer--Cartan elements in a certain dg Lie algebra of relative polyvector fields. To achieve this goal, we construct a cofibrant replacement of the operad controlling coisotropic morphisms by analogy with the Swiss-cheese operad which can be of independent interest. Finally, we show that morphisms of shifted Poisson algebras are identified with coisotropic structures on their graph.Comment: 49 pages. v2: many proofs rewritten and the paper is split into two part
Derived coisotropic structures I: affine case
derived coisotropic structures i: affine case
coisotropic morphisms commutative algebras shifted poisson i.e. algebras. roughly speaking coisotropic morphism acting algebra. coisotropic maurer cartan polyvector fields. goal cofibrant replacement operad controlling coisotropic morphisms analogy swiss cheese operad interest. morphisms shifted poisson algebras coisotropic pages. proofs rewritten split
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83848170
10.1007/s00029-018-0407-1
We extend results about $n$-shifted coisotropic structures from part I of this work to the setting of derived Artin stacks. We show that an intersection of coisotropic morphisms carries a Poisson structure of shift one less. We also compare non-degenerate shifted coisotropic structures and shifted Lagrangian structures and show that there is a natural equivalence between the two spaces in agreement with the classical result. Finally, we define quantizations of $n$-shifted coisotropic structures and show that they exist for $n>1$.Comment: 45 pages. Contains the second half of arXiv:1608.01482v1 with new material adde
Derived coisotropic structures II: stacks and quantization
derived coisotropic structures ii: stacks and quantization
extend shifted coisotropic artin stacks. intersection coisotropic morphisms carries poisson less. degenerate shifted coisotropic shifted lagrangian equivalence result. quantizations shifted coisotropic .comment pages. adde
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83831537
10.1007/s00029-018-0412-4
We generalize Lusztig's nilpotent varieties, and Kashiwara and Saito's geometric construction of crystal graphs from the symmetric to the symmetrizable case. We also construct semicanonical functions in the convolution algebras of generalized preprojective algebras. Conjecturally these functions yield semicanonical bases of the enveloping algebras of the positive part of symmetrizable Kac-Moody algebras.Comment: 50 pages. Version 2: A few typos fixed. Final version published in Selecta Mathematic
Quivers with relations for symmetrizable Cartan matrices IV: Crystal graphs and semicanonical functions
quivers with relations for symmetrizable cartan matrices iv: crystal graphs and semicanonical functions
generalize lusztig nilpotent varieties kashiwara saito geometric symmetrizable case. semicanonical convolution algebras preprojective algebras. conjecturally semicanonical bases enveloping algebras symmetrizable moody pages. typos fixed. selecta mathematic
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73384550
10.1007/s00029-018-0423-1
The orbits of the orthogonal and symplectic groups on the flag variety are in bijection, respectively, with the involutions and fixed-point-free involutions in the symmetric group $S_n$. Wyser and Yong have described polynomial representatives for the cohomology classes of the closures of these orbits, which we denote as $\hat{\mathfrak{S}}_y$ (to be called involution Schubert polynomials) and $\hat{\mathfrak{S}}^{\tt FPF}_y$ (to be called fixed-point-free involution Schubert polynomials). Our main results are explicit formulas decomposing the product of $\hat{\mathfrak{S}}_y$ (respectively, $\hat{\mathfrak{S}}^{\tt FPF}_y$) with any $y$-invariant linear polynomial as a linear combination of other involution Schubert polynomials. These identities serve as analogues of Lascoux and Sch\"utzenberger's transition formula for Schubert polynomials, and lead to a self-contained algebraic proof of the nontrivial equivalence of several definitions of $\hat{\mathfrak{S}}_y$ and $\hat{\mathfrak{S}}^{\tt FPF}_y$ appearing in the literature. Our formulas also imply combinatorial identities about involution words, certain variations of reduced words for involutions in $S_n$. We construct operators on involution words based on the Little map to prove these identities bijectively. The proofs of our main theorems depend on some new technical results, extending work of Incitti, about covering relations in the Bruhat order of $S_n$ restricted to involutions.Comment: 31 pages; v2: updated references and acknowledgments; v3: added references, minor corrections; v4: a few more references, examples, and corrections, final versio
Transition formulas for involution Schubert polynomials
transition formulas for involution schubert polynomials
orbits orthogonal symplectic flag bijection involutions involutions wyser yong representatives cohomology closures orbits mathfrak involution schubert polynomials mathfrak involution schubert polynomials formulas decomposing mathfrak mathfrak involution schubert polynomials. identities serve analogues lascoux utzenberger schubert polynomials algebraic nontrivial equivalence definitions mathfrak mathfrak appearing literature. formulas imply combinatorial identities involution involutions involution identities bijectively. proofs theorems extending incitti covering bruhat restricted pages updated acknowledgments minor versio
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73372313
10.1007/s00029-018-0429-8
We give an explicit description of the trace, or Hochschild homology, of the quantum Heisenberg category defined by Licata and Savage. We also show that as an algebra, it is isomorphic to "half" of a central extension of the elliptic Hall algebra of Burban and Schiffmann, specialized at $\sigma = \bar\sigma^{-1} = q$. A key step in the proof may be of independent interest: we show that the sum (over $n$) of the Hochschild homologies of the positive affine Hecke algebras $\mathrm{AH}_n^+$ is again an algebra, and that this algebra injects into both the elliptic Hall algebra and the trace of the $q$-Heisenberg category. Finally, we show that a natural action of the trace algebra on the space of symmetric functions agrees with the specialization of an action constructed by Schiffmann and Vasserot using Hilbert schemes.Comment: 49 pages, numerous figure
The Elliptic Hall algebra and the deformed Khovanov Heisenberg category
the elliptic hall algebra and the deformed khovanov heisenberg category
trace hochschild homology heisenberg licata savage. isomorphic elliptic hall burban schiffmann specialized sigma sigma hochschild homologies affine hecke algebras mathrm injects elliptic hall trace heisenberg category. trace agrees specialization schiffmann vasserot hilbert pages numerous
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93950215
10.1007/s00029-018-0434-y
A geometric approach to immersion formulas for soliton surfaces is provided through new cohomologies on spaces of special types of $\mathfrak{g}$-valued differential forms. This leads us to introduce Poincar\'e-type lemmas for these cohomologies, which appropriately describe the integrability conditions of Lax pairs associated with systems of PDEs. Our methods clarify the structure and properties of the deformations and soliton surfaces for the aforesaid Lax pairs. Our findings also allow for the generalization of the theory of soliton surfaces in Lie algebras to general soliton submanifolds. Techniques from the theory of infinite-dimensional jet manifolds and diffieties enable us to justify certain common assumptions of the theory of soliton surfaces. Theoretical results are illustrated through $\mathbb{C}P^{N-1}$ sigma models.Comment: 30 pages. Several typos corrected and some comments adde
A cohomological approach to immersed submanifolds via integrable systems
a cohomological approach to immersed submanifolds via integrable systems
geometric immersion formulas soliton cohomologies mathfrak valued forms. poincar lemmas cohomologies appropriately integrability pdes. clarify deformations soliton aforesaid pairs. generalization soliton algebras soliton submanifolds. infinite manifolds diffieties enable justify assumptions soliton surfaces. illustrated mathbb sigma pages. typos corrected comments adde
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73410536
10.1007/s00029-018-0435-x
We introduce a new link invariant called the algebraic genus, which gives an upper bound for the topological slice genus of links. In fact, the algebraic genus is an upper bound for another version of the slice genus proposed here: the minimal genus of a surface in the four-ball whose complement has infinite cyclic fundamental group. We characterize the algebraic genus in terms of cobordisms in three-space, and explore the connections to other knot invariants related to the Seifert form, the Blanchfield form, knot genera and unknotting. Employing Casson-Gordon invariants, we discuss the algebraic genus as a candidate for the optimal upper bound for the topological slice genus that is determined by the S-equivalence class of Seifert matrices.Comment: 29 pages, 5 figures, comments welcome! V2: Improved exposition and figures, added an example, implemented referee's recommendations. Accepted for publication in Selecta Mathematic
On classical upper bounds for slice genera
on classical upper bounds for slice genera
algebraic genus topological slice genus links. algebraic genus slice genus genus ball complement infinite cyclic group. characterize algebraic genus cobordisms explore connections knot invariants seifert blanchfield knot genera unknotting. employing casson gordon invariants algebraic genus candidate topological slice genus equivalence seifert pages comments welcome exposition implemented referee recommendations. publication selecta mathematic
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2574315
10.1007/s00030-003-1051-8
We study the Hamilton-Jacobi equation for undiscounted exit time control problems with general nonnegative Lagrangians using the dynamic programming approach. We prove theorems characterizing the value function as the unique bounded-from-below viscosity solution of the Hamilton-Jacobi equation which is null on the target. The result applies to problems with the property that all trajectories satisfying a certain integral condition must stay in a bounded set. We allow problems for which the Lagrangian is not uniformly bounded below by positive constants, in which the hypotheses of the known uniqueness results for Hamilton-Jacobi equations are not satisfied. We apply our theorems to eikonal equations from geometric optics, shape-from-shading equations from image processing, and variants of the Fuller Problem.Comment: 29 pages, 0 figures, accepted for publication in NoDEA Nonlinear Differential Equations and Applications on July 29, 200
Bounded-From-Below Solutions of the Hamilton-Jacobi Equation for Optimal Control Problems with Exit Times: Vanishing Lagrangians, Eikonal Equations, and Shape-From-Shading
bounded-from-below solutions of the hamilton-jacobi equation for optimal control problems with exit times: vanishing lagrangians, eikonal equations, and shape-from-shading
hamilton jacobi undiscounted exit nonnegative lagrangians programming approach. theorems characterizing viscosity hamilton jacobi target. applies trajectories satisfying stay set. lagrangian uniformly hypotheses uniqueness hamilton jacobi satisfied. theorems eikonal geometric optics shading variants fuller pages publication nodea
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29513144
10.1007/s00030-007-2047-6
In this paper, we consider a time independent $C^2$ Hamiltonian, sa\-tisfying the usual hypothesis of the classical Calculus of Variations, on a non-compact connected manifold. Using the Lax-Oleinik semigroup, we give a proof of the existence of weak KAM solutions, or viscosity solutions, for the associated Hamilton-Jacobi Equation. This proof works also in presence of symmetries. We also study the role of the amenability of the group of symmetries to understand when the several critical values that can be associated with the Hamiltonian coincide.Comment: arXiv admin note: text overlap with arXiv:1004.0086 by other author
Weak KAM theorem on non compact manifolds
weak kam theorem on non compact manifolds
tisfying usual calculus manifold. oleinik semigroup viscosity hamilton jacobi equation. symmetries. amenability symmetries admin overlap
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36728444
10.1007/s00030-009-0023-z
The article of record as published may be located at http://dx.doi.org/10.1007/s00030-009-0023-zIn this work, we first prove the existence and uniqueness of a strong solution to stochastic GOY model of turbulence with a small multiplicative noise. Then using the weak convergence approach, Laplace principle for solutions of the stochastic GOY model is established in certain Polish space. Thus a Wentzell-Freidlin type large deviation principle is established utilizing certain results by Varadhan and Bryc
Large deviations for the stochastic shell model of turbulence
large deviations for the stochastic shell model of turbulence
record uniqueness stochastic turbulence multiplicative noise. laplace stochastic polish space. wentzell freidlin utilizing varadhan bryc
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2811769
10.1007/s00030-011-0105-6
Countable families of global-in-time and blow-up similarity sign-changing patterns of the Cauchy problem for the fourth-order thin film equation (TFE-4) ut= -del . (|u|(n)del Delta u) in R(N) x R(+), where n > 0, are studied. The similarity solutions are of standard "forward" and "backward" forms u(+/-)(x, t) = (+/- t)(-alpha)f(y), y = x/(+/- t)(beta), beta = 1-alpha n/4, +/- t>0, where f solve Bn+(alpha, f)equivalent to-del.(|f|n del Delta f)+/-beta y.del f +/-alpha f = 0 in RN, (0.1) and alpha is an element of R is a parameter (a "nonlinear eigenvalue"). The sign "+", i.e.,t > 0, corresponds to global asymptotics as t -> +infinity, while "-" (t < 0) yields blow-up limits t -> 0(-) describing possible "micro-scale" (multiple zero) structures of solutions of the PDE. To get a countable set of nonlinear pairs {f(gamma), alpha(gamma)}, a bifurcation-branching analysis is performed by using a homotopy path n -> 0(+) in (0.1), where B(0)(+/-) (alpha, f) become associated with a pair {B, B*} of linear non-self-adjoint operators B=-Delta(2) + 1/4 y.del+N/4 I and B*=-Delta(2) - 1/4y.( so (B)*(L2) = B*), which are known to possess a discrete real spectrum, sigma(B) = sigma(B*) = {lambda(gamma) = - |gamma/4|}(|gamma|>0) (gamma is a multiindex in R(N)). These operators occur after corresponding global and blow-up scaling of the classic bi-harmonic equation u(t) = -Delta(2)u. This allows us to trace out the origin of a countable family of n-branches of nonlinear eigenfunctions by using simple or semi-simple eigenvalues of the linear operators {B, B*} leading to important properties of oscillatory sign-changing nonlinear patterns of the TFE, at least, for small n > 0
Local bifurcation-branching analysis of global and "blow-up" patterns for a fourth-order thin film equation
local bifurcation-branching analysis of global and "blow-up" patterns for a fourth-order thin film equation
countable families blow similarity changing cauchy fourth film delta studied. similarity backward alpha beta beta alpha solve alpha del. delta beta alpha alpha eigenvalue i.e. asymptotics infinity blow describing micro pde. countable gamma alpha gamma bifurcation branching homotopy alpha adjoint delta delta possess sigma sigma lambda gamma gamma gamma gamma multiindex blow classic harmonic delta trace countable branches eigenfunctions eigenvalues oscillatory changing
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2116386
10.1007/s00030-011-0107-4
A simple version of exact finite dimensional reduction for the variational setting of mechanical systems is presented. It is worked out by means of a thorough global version of the implicit function theorem for monotone operators. Moreover, the Hessian of the reduced function preserves all the relevant information of the original one, by Schur's complement, which spontaneously appears in this context. Finally, the results are straightforwardly extended to the case of a Dirichlet problem on a bounded domain.Comment: 13 pages; v2: minor changes, to appear in Nonlinear Differential Equations and Application
Finite reduction and Morse index estimates for mechanical systems
finite reduction and morse index estimates for mechanical systems
variational presented. worked thorough implicit monotone operators. hessian preserves schur complement spontaneously context. straightforwardly dirichlet pages minor
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54039251
10.1007/s00030-011-0148-8
International audienceWe study the Cauchy-Dirichlet problem for the elliptic-parabolic equation $$b(u)_t +\div F(u) - \Delta u=f$$ in a bounded domain. We do not assume the structure condition ''$b(z)=b(\hat z) \Rightarrow F(z)=F(\hat z)$''. Our main goal is to investigate the problem of continuous dependence of the solutions on the data of the problem and the question of convergence of discretization methods. As in the work of Ammar and Wittbold \cite{AmmarWittbold} where existence was established, monotonicity and penalization are the main tools of our study. In the case of a Lipschitz continuous flux $F$, we justify the uniqueness of $u$ (the uniqueness of $b(u)$ is well-known) and prove the continuous dependence in $L^1$ for the case of strongly convergent finite energy data. We also prove convergence of the $\varepsilon$-discretized solutions used in the semigroup approach to the problem; and we prove convergence of a monotone time-implicit finite volume scheme. In the case of a merely continuous flux $F$, we show that the problem admits a maximal and a minimal solution
Convergence of approximate solutions to an elliptic-parabolic equation without the structure condition
convergence of approximate solutions to an elliptic-parabolic equation without the structure condition
audiencewe cauchy dirichlet elliptic parabolic delta domain. rightarrow goal discretization methods. ammar wittbold cite ammarwittbold monotonicity penalization study. lipschitz justify uniqueness uniqueness convergent data. varepsilon discretized semigroup monotone implicit scheme. merely admits maximal
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47104741
10.1007/s00030-012-0155-4
26 pagesInternational audienceThe hydrodynamic limit for a kinetic model of chemotaxis is investigated. The limit equation is a non local conservation law, for which finite time blow-up occurs, giving rise to measure-valued solutions and discontinuous velocities. An adaptation of the notion of duality solutions, introduced for linear equations with discontinuous coefficients, leads to an existence result. Uniqueness is obtained through a precise definition of the nonlinear flux as well as the complete dynamics of aggregates, i.e. combinations of Dirac masses. Finally a particle method is used to build an adapted numerical scheme
Chemotaxis: from kinetic equations to aggregate dynamics
chemotaxis: from kinetic equations to aggregate dynamics
pagesinternational audiencethe hydrodynamic chemotaxis investigated. conservation blow giving valued discontinuous velocities. adaptation notion duality discontinuous result. uniqueness precise aggregates i.e. combinations dirac masses. build adapted
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52905238
10.1007/s00030-012-0156-3
International audienceWe consider the asymptotic behavior of an evolving weakly coupled Fokker-Planck system of two equations set in a periodic environment. The magnitudes of the diffusion and the coupling are respectively proportional and inversely proportional to the size of the period. We prove that, as the period tends to zero, the solutions of the system either propagate (concentrate) with a fixed constant velocity (determined by the data) or do not move at all. The system arises in the modeling of motor proteins which can take two different states. Our result implies that, in the limit, the molecules either move along a filament with a fixed direction and constant speed or remain immobile
A homogenization approach for the motion of motor proteins
a homogenization approach for the motion of motor proteins
audiencewe asymptotic evolving weakly fokker planck environment. magnitudes inversely period. tends propagate concentrate move all. arises motor states. move filament immobile
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55621257
10.1007/s00030-012-0204-z
For the initial value problem (IVP) associated to the generalized Korteweg-de Vries (gKdV) equation with supercritical nonlinearity, \begin{equation*} u_{t}+\partial_x^3u+\partial_x(u^{k+1}) =0,\qquad k\geq 5, \end{equation*} numerical evidence [Bona J.L., Dougalis V.A., Karakashian O.A., McKinney W.R.: Conservative, high-order numerical schemes for the generalized Korteweg–de Vries equation. Philos. Trans. Roy. Soc. London Ser. A 351, 107–164 (1995) ] shows that, there are initial data $\phi\in H^1(\mathbb{R})$ such that the corresponding solution may blow-up in finite time. Also, with the evidence from numerical simulation [Abdullaev F.K., Caputo J.G., Kraenkel R.A., Malomed B.A.: Controlling collapse in Bose–Einstein condensates by temporal modulation of the scattering length. Phys. Rev. A 67, 012605 (2003) and Konotop V.V., Pacciani P.: Collapse of solutions of the nonlinear Schrödinger equation with a time dependent nonlinearity: application to the Bose–Einstein condensates. Phys. Rev. Lett. 94, 240405 (2005) ], it has been claimed that a periodic time dependent coefficient in the nonlinearity would disturb the blow-up solution, either accelerating or delaying it. In this work, we investigate the IVP associated to the gKdV equation \begin{equation*} u_{t}+\partial_x^3u+g(\omega t)\partial_x(u^{k+1}) =0, \end{equation*} where $g$ is a periodic function and $k\geq 5$ is an integer. We prove that, for given initial data $\phi \in H^1(\mathbb{R})$, as $|\omega|\to \infty$, the solution $u_{\omega}$ converges to the solution $U$ of the initial value problem associated to \begin{equation*} U_{t}+\partial_x^3U+m(g)\partial_x(U^{k+1}) =0, \end{equation*} with the same initial data, where $m(g)$ is the average of the periodic function $g$. Moreover, if the solution $U$ is global and satisfies $\|U\|_{L_x^5L_t^{10}}<\infty$, then we prove that the solution $u_{\omega}$ is also global provided $|\omega|$ is sufficiently large.M. P. was partially supported by the Research Center of Mathematics of the University of Minho, Portugal through the FCT Pluriannual Funding Program, and through the project PTDC/MAT/109844/2009, and M. S. was partially supported by FAPESP Brazil
On the supercritical KDV equation with time-oscillating nonlinearity
on the supercritical kdv equation with time-oscillating nonlinearity
korteweg vries gkdv supercritical nonlinearity begin qquad bona j.l. dougalis v.a. karakashian o.a. mckinney w.r. conservative schemes korteweg–de vries equation. philos. trans. roy. soc. ser. mathbb blow time. abdullaev f.k. caputo j.g. kraenkel r.a. malomed b.a. controlling collapse bose–einstein condensates modulation length. phys. rev. konotop v.v. pacciani collapse schrödinger nonlinearity bose–einstein condensates. phys. rev. lett. claimed nonlinearity disturb blow accelerating delaying gkdv begin omega integer. mathbb omega infty omega converges begin satisfies infty omega omega sufficiently large.m. partially mathematics minho portugal pluriannual funding ptdc partially fapesp brazil
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5236932
10.1007/s00030-013-0220-7
We study the long time behavior of solutions of the Cauchy problem for nonlinear reaction-diffusion equations in one space dimension with the nonlinearity of bistable, ignition or monostable type. We prove a one-to-one relation between the long time behavior of the solution and the limit value of its energy for symmetric decreasing initial data in $L^2$ under minimal assumptions on the nonlinearities. The obtained relation allows to establish sharp threshold results between propagation and extinction for monotone families of initial data in the considered general setting
Threshold phenomena for symmetric decreasing solutions of reaction-diffusion equations
threshold phenomena for symmetric decreasing solutions of reaction-diffusion equations
cauchy nonlinearity bistable ignition monostable type. decreasing assumptions nonlinearities. establish sharp propagation extinction monotone families
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9706634
10.1007/s00030-013-0223-4
We modify the approach of Burton and Toland Comm. Pure Appl. Math. (2011) to show the existence of periodic surface water waves with vorticity in order that it becomes suited to a stability analysis. This is achieved by enlarging the function space to a class of stream functions that do not correspond necessarily to travelling profiles. In particular, for smooth profiles and smooth stream functions, the normal component of the velocity field at the free boundary is not required a priori to vanish in some Galilean coordinate system. Travelling periodic waves are obtained by a direct minimisation of a functional that corresponds to the total energy and that is therefore preserved by the time-dependent evolutionary problem (this minimisation appears in Burton and Toland after a first maximisation). In addition, we not only use the circulation along the upper boundary as a constraint, but also the total horizontal impulse (the velocity becoming a Lagrange multiplier). This allows us to preclude parallel flows by choosing appropriately the values of these two constraints and the sign of the vorticity. By stability, we mean conditional energetic stability of the set of minimizers as a whole, the perturbations being spatially periodic of given period
On the stability of travelling waves with vorticity obtained by minimization
on the stability of travelling waves with vorticity obtained by minimization
modify burton toland comm. appl. math. vorticity suited analysis. enlarging stream necessarily travelling profiles. stream priori vanish galilean coordinate system. travelling minimisation preserved evolutionary minimisation burton toland maximisation circulation impulse becoming lagrange multiplier preclude flows choosing appropriately vorticity. conditional energetic minimizers perturbations spatially
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24941634
10.1007/s00030-013-0258-6
In this article, we study the Fu\v{c}ik spectrum of fractional Laplace operator which is defined as the set of all $(\al,\ba)\in \mb R^2$ such that \begin{equation*} \quad \left. \begin{array}{lr} \quad (-\De)^s u = \al u^{+} - \ba u^{-} \; \text{in}\; \Om \quad \quad \quad \quad u = 0 \; \mbox{in}\; \mb R^n \setminus\Om.\\ \end{array} \quad \right\} \end{equation*} has a non-trivial solution $u$, where $\Om$ is a bounded domain in $\mb R^n$ with Lipschitz boundary, $n>2s$, $s\in(0,1)$. The existence of a first nontrivial curve $\mc C$ of this spectrum, some properties of this curve $\mc C$, e.g. Lipschitz continuous, strictly decreasing and asymptotic behavior are studied in this article. A variational characterization of second eigenvalue of the fractional eigenvalue problem is also obtained. At the end, we study a nonresonance problem with respect to Fu\v{c}ik spectrum.Comment: 22 pages in NoDEA: Nonlinear differential equations and applications, 201
On The Fu\v{c}ik Spectrum Of Non-Local Elliptic Operators
on the fu\v{c}ik spectrum of non-local elliptic operators
fractional laplace begin quad left. begin array quad quad quad quad quad mbox setminus array quad trivial lipschitz nontrivial e.g. lipschitz strictly decreasing asymptotic article. variational eigenvalue fractional eigenvalue obtained. nonresonance pages nodea
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24989724
10.1007/s00030-014-0266-1
We consider the non-linear thermoelastic plate equation in rectangular domains $\Omega$. More precisely, $\Omega$ is considered to be given as the Cartesian product of whole or half spaces and a cube. First the linearized equation is treated as an abstract Cauchy problem in $L^p$-spaces. We take advantage of the structure of $\Omega$ and apply operator-valued Fourier multiplier results to infer an $\mathcal R$-bounded $\mathcal H^\infty$-calculus. With the help of maximal $L^p$-regularity existence and uniqueness of local real-analytic strong solutions together with analytic dependency on the data is shown.Comment: 16 pages; final versio
Local Strong Solutions for the Non-Linear Thermoelastic Plate Equation on Rectangular Domains in $L^p$-Spaces
local strong solutions for the non-linear thermoelastic plate equation on rectangular domains in $l^p$-spaces
thermoelastic plate rectangular omega precisely omega cartesian cube. linearized cauchy spaces. advantage omega valued fourier multiplier infer mathcal mathcal infty calculus. maximal regularity uniqueness analytic analytic dependency pages versio
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54007894
10.1007/s00030-014-0267-0
We study the controllability for a class of semilinear differential inclusions in Banach spaces. Since we assume the regularity of the nonlinear part with respect to the weak topology, we do not require the compactness of the evolution operator generated by the linear part. As well we are not posing any conditions on the multivalued nonlinearity expressed in terms of measures of noncompactness. We are considering the usual assumption on the controllability of the associated linear problem. Notice that, in infinite dimensional spaces, the above mentioned compactness of\ud the evolution operator and linear controllability condition are in contradiction with each other. We suppose that the nonlinear term has convex, closed, bounded values and a weakly sequentially closed graph when restricted to its second argument. This regularity setting allows us to solve controllability problem under various growth conditions. As application, a controllability result for hyperbolic integro-differential equations and inclusions is obtained. In particular, we consider controllability of a system arising in a model of nonlocal spatial population dispersal and a system governed by the second order one-dimensional telegraph equation
Controllability for systems governed by semilinear evolution equations without compactness
controllability for systems governed by semilinear evolution equations without compactness
controllability semilinear inclusions banach spaces. regularity topology compactness part. posing multivalued nonlinearity noncompactness. usual controllability problem. notice infinite compactness controllability contradiction other. convex weakly sequentially restricted argument. regularity solve controllability conditions. controllability hyperbolic integro inclusions obtained. controllability arising nonlocal dispersal governed telegraph
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25047559
10.1007/s00030-015-0311-8
We provide new results on the existence, non-existence, localization and multiplicity of nontrivial solutions for systems of Hammerstein integral equations. Some of the criteria involve a comparison with the spectral radii of some associated linear operators. We apply our results to prove the existence of multiple nonzero radial solutions for some systems of elliptic boundary value problems subject to nonlocal boundary conditions. Our approach is topological and relies on the classical fixed point index. We present an example to illustrate our theory.Comment: 25 pages. arXiv admin note: text overlap with arXiv:1404.139
Nonzero radial solutions for a class of elliptic systems with nonlocal BCs on annular domains
nonzero radial solutions for a class of elliptic systems with nonlocal bcs on annular domains
localization multiplicity nontrivial hammerstein equations. involve radii operators. nonzero elliptic nonlocal conditions. topological relies index. illustrate pages. admin overlap
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29504570
10.1007/s00030-015-0315-4
We study the existence of positive viscosity solutions to Trudinger's equation for cylindrical domains $\Omega\times[0, T)$, where $\Omega\subset \mathbb{R}^n,\;n\ge 2,$ is a bounded domain, $T>0$ and $2\leq p<\infty$. We show existence for general domains $\Omega,$ when $n<p<\infty$. For $2\leq p\leq n$, we prove existence for domains $\Omega$ that satisfy a uniform outer ball condition. We achieve this by constructing suitable sub-solutions and super-solutions and applying Perron's method.Comment: 25 pages, 2 figure
On the viscosity solutions to Trudinger's equation
on the viscosity solutions to trudinger's equation
viscosity trudinger cylindrical omega omega mathbb infty omega infty omega satisfy outer ball condition. constructing super perron pages
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25047368
10.1007/s00030-015-0341-2
We study the propagation of singularities for semilinear Schrodinger equations with quadratic Hamiltonians, in particular for the semilinear harmonic oscillator. We show that the propagation still occurs along the flow the Hamiltonian flow, but for Sobolev regularities in a certain range and provided the notion of Sobolev-wave front set is conveniently modified. The proof makes use of a weighted version of the paradifferential calculus, adapted to our situation. The results can be regarded as the Schrodinger counterpart of those known for semilinear hyperbolic equations, which hold with the usual wave front set.Comment: 16 page
Propagation of singularities for semilinear Schr\"odinger equations
propagation of singularities for semilinear schr\"odinger equations
propagation singularities semilinear schrodinger quadratic hamiltonians semilinear harmonic oscillator. propagation sobolev regularities notion sobolev front conveniently modified. weighted paradifferential calculus adapted situation. regarded schrodinger counterpart semilinear hyperbolic hold usual front
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29556415
10.1007/s00030-015-0350-1
We generalize the notion of renormalized solution to semilinear elliptic and parabolic equations involving operator associated with general (possibly nonlocal) regular Dirichlet form and smooth measure on the right-hand side. We show that under mild integrability assumption on the data a quasi-continuous function $u$ is a renormalized solution to an elliptic (or parabolic) equation in the sense of our definition iff $u$ is its probabilistic solution, i.e. $u$ can be represented by a suitable nonlinear Feynman-Kac formula. This implies in particular that for a broad class of local and nonlocal semilinear equations there exists a unique renormalized solution
Renormalized solutions of semilinear equations involving measure data and operator corresponding to Dirichlet form
renormalized solutions of semilinear equations involving measure data and operator corresponding to dirichlet form
generalize notion renormalized semilinear elliptic parabolic involving possibly nonlocal dirichlet side. mild integrability quasi renormalized elliptic parabolic probabilistic i.e. feynman formula. broad nonlocal semilinear renormalized
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48159764
10.1007/s00030-016-0401-2
article 47International audienceWe study existence and uniqueness of the invariant measure for a stochastic process with degenerate diffusion, whose infinitesimal generator is a linear subelliptic operator in the whole space R N with coefficients that may be unbounded. Such a measure together with a Liouville-type theorem will play a crucial role in two applications: the ergodic problem studied through stationary problems with vanishing discount and the long time behavior of the solution to a parabolic Cauchy problem. In both cases, the constants will be characterized in terms of the invariant measure
The ergodic problem for some subelliptic operators with unbounded coefficients
the ergodic problem for some subelliptic operators with unbounded coefficients
audiencewe uniqueness stochastic degenerate infinitesimal generator subelliptic unbounded. liouville crucial ergodic stationary vanishing discount parabolic cauchy problem.
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42706979
10.1007/s00030-016-0408-8
We study the Cauchy problem for a nonlinear damped wave equation. Under suitable assumptions for the nonlinearity and the initial data, we obtain the global solution which satisfies weighted $L^1$ and $L^\infty$ estimates. Furthermore, we establish the higher order asymptotic expansion of the solution. This means that we construct the nonlinear approximation of the global solution with respect to the weight of the data. Our proof is based on the approximation formula of the linear solution, which is given in [36], and the nonlinear approximation theory for a nonlinear parabolic equation developed by [18]
Higher order asymptotic expansions to the solutions for a nonlinear damped wave equation
higher order asymptotic expansions to the solutions for a nonlinear damped wave equation
cauchy damped equation. assumptions nonlinearity satisfies weighted infty estimates. establish asymptotic solution. data. parabolic
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29540736
10.1007/s00030-016-0411-0
We prove existence and multiplicity results for finite energy solutions to the nonlinear elliptic equation \[ -\triangle u+V\left( \left| x\right| \right) u=g\left( \left| x\right| ,u\right) \quad \textrm{in }\Omega \subseteq \mathbb{R}^{N},\ N\geq 3, \] where $\Omega $ is a radial domain (bounded or unbounded) and $u$ satisfies $u=0$ on $\partial \Omega $ if $\Omega \neq \mathbb{R}^{N}$ and $u\rightarrow 0$ as $\left| x\right| \rightarrow \infty $ if $\Omega $ is unbounded. The potential $V$ may be vanishing or unbounded at zero or at infinity and the nonlinearity $g$ may be superlinear or sublinear. If $g$ is sublinear, the case with $g\left( \left| \cdot \right| ,0\right) \neq 0$ is also considered.Comment: 29 pages, 8 figure
Compactness and existence results in weighted Sobolev spaces of radial functions. Part II: Existence
compactness and existence results in weighted sobolev spaces of radial functions. part ii: existence
multiplicity elliptic triangle quad textrm omega subseteq mathbb omega unbounded satisfies omega omega mathbb rightarrow rightarrow infty omega unbounded. vanishing unbounded infinity nonlinearity superlinear sublinear. sublinear cdot pages
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42745274
10.1007/s00030-016-0424-8
We consider the nonlinear Choquard equation $$ -\Delta u+V u=(I_\alpha \ast \vert u\vert ^p)\vert u\vert ^{p-2}u \qquad \text{ in } \mathbb{R}^N $$ where $N\geq 1$, $I_\alpha$ is the Riesz potential integral operator of order $\alpha \in (0, N)$ and $p > 1$. If the potential $ V \in C (\mathbb{R}^N; [0,+\infty)) $ satisfies the confining condition $$ \liminf\limits_{\vert x\vert \to +\infty}\frac{V(x)}{1+\vert x\vert ^{\frac{N+\alpha}{p}-N}}=+\infty, $$ and $\frac{1}{p} > \frac{N - 2}{N + \alpha}$, we show the existence of a groundstate, of an infinite sequence of solutions of unbounded energy and, when $p \ge 2$ the existence of least energy nodal solution. The constructions are based on suitable weighted compact embedding theorems. The growth assumption is sharp in view of a Poho\v{z}aev identity that we establish.Comment: 21 page
Choquard equations under confining external potentials
choquard equations under confining external potentials
choquard delta alpha vert vert vert vert qquad mathbb alpha riesz alpha mathbb infty satisfies confining liminf vert vert infty frac vert vert frac alpha infty frac frac alpha groundstate infinite unbounded nodal solution. constructions weighted embedding theorems. sharp poho
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42724468
10.1007/s00030-017-0434-1
We study the Cauchy problem for the nonlinear damped wave equation and establish the large data local well-posedness and small data global well-posedness with slowly decaying initial data. We also prove that the asymptotic profile of the global solution is given by a solution of the corresponding parabolic problem, which shows that the solution of the damped wave equation has the diffusion phenomena. Moreover, we show blow-up of solution and give the estimate of the lifespan for a subcritical nonlinearity. In particular, we determine the critical exponent for any space dimension.Comment: 43 pages. Theorem 1.3 is improved, some errors are corrected and references are update
The Cauchy problem for the nonlinear damped wave equation with slowly decaying data
the cauchy problem for the nonlinear damped wave equation with slowly decaying data
cauchy damped establish posedness posedness slowly decaying data. asymptotic parabolic damped phenomena. blow lifespan subcritical nonlinearity. exponent pages. corrected update
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29506022
10.1007/s00030-017-0436-z
This paper concerns integral varifolds of arbitrary dimension in an open subset of Euclidean space satisfying integrability conditions on their first variation. Firstly, the study of pointwise power decay rates almost everywhere of the quadratic tilt-excess is completed by establishing the precise decay rate for two-dimensional integral varifolds of locally bounded first variation. In order to obtain the exact decay rate, a coercive estimate involving a height-excess quantity measured in Orlicz spaces is established. Moreover, counter-examples to pointwise power decay rates almost everywhere of the super-quadratic tilt-excess are obtained. These examples are optimal in terms of the dimension of the varifold and the exponent of the integrability condition in most cases, for example if the varifold is not two-dimensional. These examples also demonstrate that within the scale of Lebesgue spaces no local higher integrability of the second fundamental form, of an at least two-dimensional curvature varifold, may be deduced from boundedness of its generalised mean curvature vector. Amongst the tools are Cartesian products of curvature varifolds.Comment: mainly extended the overview section; updated reference
Decay rates for the quadratic and super-quadratic tilt-excess of integral varifolds
decay rates for the quadratic and super-quadratic tilt-excess of integral varifolds
concerns varifolds euclidean satisfying integrability variation. firstly pointwise everywhere quadratic tilt excess completed establishing precise varifolds locally variation. coercive involving excess quantity orlicz established. counter pointwise everywhere super quadratic tilt excess obtained. varifold exponent integrability varifold dimensional. lebesgue integrability curvature varifold deduced boundedness generalised curvature vector. amongst cartesian curvature overview updated
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42663733
10.1007/s00030-017-0457-7
We study the mean curvature flow of graphs both with Neumann boundary conditions and transport terms. We derive boundary gradient estimates for the mean curvature flow. As an application, the existence of the mean curvature flow of graphs is presented. A key argument is a boundary monotonicity formula of a Huisken type derived using reflected backward heat kernels. Furthermore, we provide regularity conditions for the transport terms.Comment: 21 pages, 3 figures, Accepted for publication in "NoDEA. Nonlinear Differential Equations and Applications
Gradient estimates for mean curvature flow with Neumann boundary conditions
gradient estimates for mean curvature flow with neumann boundary conditions
curvature neumann terms. derive curvature flow. curvature presented. argument monotonicity huisken reflected backward kernels. regularity pages publication nodea.
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73957174
10.1007/s00030-017-0468-4
The purpose of this paper is to investigate the time behavior of the solution of a weighted $p$-Laplacian evolution equation, given by \begin{align} \label{eveq} \begin{cases} u_{t} = \text{div} \left(\gamma |\nabla u|^{p-2}\nabla u \right) & \text{on} (0,\infty)\times S, \\ \gamma|\nabla u|^{p-2}\nabla u\cdot\eta=0 & \text{on} (0,\infty)\times \partial S, \\ u(0,\cdot)=u_{0} & \text{on} S,\end{cases} \end{align} where $n \in \mathbb{N}\setminus \{1\}$, $p \in (1,\infty)\setminus \{2\}$, $S\subseteq \mathbb{R}^{n}$ is an open, bounded and connected set of class $C^{1}$, $\eta$ is the unit outer normal on $\partial S $, and $\gamma: S \rightarrow (0,\infty)$ is a bounded function which can be extended to an $A_{p}$-Muckenhoupt weight on $\mathbb{R}^{n}$. It will be proven that the solution converges in $L^{1}(S)$ to the average of the initial value $u_{0} \in L^{1}(S)$. Moreover, a conservation of mass principle, an extinction principle and a decay rate for the solution will be derived.Comment: The final paper is published in NoDEA (August 2017 - Volume 24 Issue 4) at http://link.springer.co
Asymptotic Results for Solutions of a weighted p-Laplacian evolution Equation with Neumann Boundary Conditions
asymptotic results for solutions of a weighted p-laplacian evolution equation with neumann boundary conditions
weighted laplacian begin align label eveq begin gamma nabla nabla infty gamma nabla nabla cdot infty cdot align mathbb setminus infty setminus subseteq mathbb outer gamma rightarrow infty muckenhoupt mathbb proven converges conservation extinction nodea august link.springer.co
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42668583
10.1007/s00030-017-0477-3
We introduce a class of stochastic Allen-Cahn equations with a mobility coefficient and colored noise. For initial data with finite free energy, we analyze the corresponding Cauchy problem on the $d$-dimensional torus in the time interval $[0,T]$. Assuming that $d\le 3$ and that the potential has quartic growth, we prove existence and uniqueness of the solution as a process $u$ in $L^2$ with continuous paths, satisfying almost surely the regularity properties $u\in C([0,T]; H^1)$ and $u\in L^2([0,T];H^2)$.Comment: 34 page
Stochastic Allen-Cahn equation with mobility
stochastic allen-cahn equation with mobility
stochastic allen cahn mobility colored noise. analyze cauchy torus quartic uniqueness paths satisfying surely regularity .comment
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42728478
10.1007/s00030-017-0487-1
In this article, we study the Brezis-Nirenberg type problem of nonlinear Choquard equation involving a fractional Laplacian \[ (-\De)^s u = \left( \int_{\Om}\frac{|u|^{2^*_{\mu,s}}}{|x-y|^{\mu}}\mathrm{d}y \right)|u|^{2^*_{\mu,s}-2}u +\la u \; \text{in } \Om,\] where $\Om $ is a bounded domain in $\mathbb R^n$ with Lipschitz boundary, $\la $ is a real parameter, $s \in (0,1)$, $n >2s$ and $2^*_{\mu,s}= (2n-\mu)/(n-2s)$ is the critical exponent in the sense of Hardy-Littlewood-Sobolev inequality. We obtain some existence, multiplicity, regularity and nonexistence results for solution of the above equation using variational methods.Comment: 32 pages. arXiv admin note: text overlap with arXiv:1604.00826 by other author
Fractional Choquard Equation with Critical Nonlinearities
fractional choquard equation with critical nonlinearities
brezis nirenberg choquard involving fractional laplacian frac mathrm mathbb lipschitz exponent hardy littlewood sobolev inequality. multiplicity regularity nonexistence variational pages. admin overlap
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42740271
10.1007/s00030-018-0500-3
We show that the characterization of existence and uniqueness up to vertical translations of solutions to the prescribed mean curvature equation, originally proved by Giusti in the smooth case, holds true for domains satisfying very mild regularity assumptions. Our results apply in particular to the non-parametric solutions of the capillary problem for perfectly wetting fluids in zero gravity. Among the essential tools used in the proofs, we mention a \textit{generalized Gauss-Green theorem} based on the construction of the weak normal trace of a vector field with bounded divergence, in the spirit of classical results due to Anzellotti, and a \textit{weak Young's law} for $(\Lambda,r_{0})$-minimizers of the perimeter.Comment: 23 pages, 1 figure --- The results on the weak normal trace of vector fields have been now extended and moved in a self-contained paper available at: arXiv:1708.0139
The prescribed mean curvature equation in weakly regular domains
the prescribed mean curvature equation in weakly regular domains
uniqueness translations prescribed curvature originally proved giusti satisfying mild regularity assumptions. parametric capillary perfectly wetting fluids gravity. proofs mention textit gauss trace divergence spirit anzellotti textit lambda minimizers pages trace moved
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129348271
10.1007/s00030-018-0504-z
This paper considers a pair of coupled nonlinear Helmholtz equations \begin{align*} -\Delta u - \mu u = a(x) \left( |u|^\frac{p}{2} + b(x) |v|^\frac{p}{2} \right)|u|^{\frac{p}{2} - 2}u, \end{align*} \begin{align*} -\Delta v - \nu v = a(x) \left( |v|^\frac{p}{2} + b(x) |u|^\frac{p}{2} \right)|v|^{\frac{p}{2} - 2}v \end{align*} on $\mathbb{R}^N$ where $\frac{2(N+1)}{N-1} < p < 2^\ast$. The existence of nontrivial strong solutions in $W^{2, p}(\mathbb{R}^N)$ is established using dual variational methods. The focus lies on necessary and sufficient conditions on the parameters deciding whether or not both components of such solutions are nontrivial.Comment: Published version. Contains minor revisions: Quote added, explanations on p.12 concerning F_{\mu\nu} = \infty, correction of exponent on p.1
Dual Variational Methods for a nonlinear Helmholtz system
dual variational methods for a nonlinear helmholtz system
considers helmholtz begin align delta frac frac frac align begin align delta frac frac frac align mathbb frac nontrivial mathbb variational methods. lies deciding version. minor revisions quote explanations concerning infty exponent
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2560500
10.1007/s00031-004-7010-6
Let $X$ be a smooth projective curve over the complex numbers. To every representation $\rho\colon \GL(r)\lra \GL(V)$ of the complex general linear group on the finite dimensional complex vector space $V$ which satisfies the assumption that there be an integer $\alpha$ with $\rho(z \id_{\C^r})=z^\alpha \id_V$ for all $z\in\C^*$ we associate the problem of classifying triples $(E,L,\phi)$ where $E$ is a vector bundle of rank $r$ on $X$, $L$ is a line bundle on $X$, and $\phi\colon E_\rho\lra L$ is a non trivial homomorphism. Here, $E_\rho$ is the vector bundle of rank $\dim V$ associated to $E$ via $\rho$. If we take, for example, the standard representation of $\GL(r)$ on $\C^r$ we have to classify triples $(E,L,\phi)$ consisting of $E$ as before and a non-zero homomorphism $\phi\colon E\lra L$ which includes the so-called Bradlow pairs. For the representation of $\GL(r)$ on $S^2\C^3$ we find the conic bundles of Gomez and Sols. In the present paper, we will formulate a general semistability concept for the above triples which depends on a rational parameter $\delta$ and establish the existence of moduli spaces of $\delta$-(semi)stable triples of fixed topological type. The notion of semistability mimics the Hilbert-Mumford criterion for $SL(r)$ which is the main reason that such a general approach becomes feasible. In the known examples (the above, Higgs bundles, extension pairs, oriented framed bundles) we show how to recover the "usual" semistability concept. This process of simplification can also be formalized. Altogether, our results provide a unifying construction for the moduli spaces of most decorated vector bundle problems together with an automatism for finding the right notion of semistability and should therefore be of some interest.Comment: Final Version (To appear in Transformation Groups); V2: Example 3.7 corrected, other minor modifications; V3: Notion of polystability corrected, other minor modification
A universal construction for moduli spaces of decorated vector bundles over curves
a universal construction for moduli spaces of decorated vector bundles over curves
projective numbers. colon satisfies integer alpha alpha associate classifying triples bundle bundle colon trivial homomorphism. bundle classify triples consisting homomorphism colon bradlow pairs. conic bundles gomez sols. formulate semistability triples rational delta establish moduli delta triples topological type. notion semistability mimics hilbert mumford criterion feasible. bundles oriented framed bundles recover usual semistability concept. simplification formalized. altogether unifying moduli decorated bundle automatism notion semistability corrected minor modifications notion polystability corrected minor modification
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2583409
10.1007/s00031-005-0402-4
We construct the action of the quantum group U_v(sl_n) by the natural correspondences in the equivariant localized $K$-theory of the Laumon based Quasiflags' moduli spaces. The resulting module is the universal Verma module. We construct geometrically the Shapovalov scalar product and the Whittaker vectors. It follows that a certain generating function of the characters of the global sections of the structure sheaves of the Laumon moduli spaces satisfies a $v$-difference analogue of the quantum Toda lattice system, reproving the main theorem of Givental-Lee. The similar constructions are performed for the affine Lie agebra \hat{sl}_n.Comment: Some corrections are made in Sections 2,
Finite difference quantum Toda lattice via equivariant K-theory
finite difference quantum toda lattice via equivariant k-theory
correspondences equivariant localized laumon quasiflags moduli spaces. module universal verma module. geometrically shapovalov whittaker vectors. generating characters sheaves laumon moduli satisfies analogue toda reproving givental lee. constructions affine agebra
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2572052
10.1007/s00031-005-1101-x
Let k be a field, n a positive integer, X a generic nxn matrix over k (i.e., a matrix (x_{ij}) of n^2 independent indeterminates over the polynomial ring k[x_{ij}]), and adj(X) its classical adjoint. It is shown that if char k=0 and n is odd, then adj(X) is not the product of two noninvertible nxn matrices over k[x_{ij}]. If n is even and >2, a restricted class of nontrivial factorizations occur. The nonzero-characteristic case remains open. The operation adj on matrices arises from the (n-1)st exterior power functor on modules; the same question can be posed for matrix operations arising from other functors.Comment: Revised version contains answer to "even n" question left open in original version. (Answer due to Buchweitz & Leuschke; simple proof in this note.) Copy at http://math.berkeley.edu/~gbergman/papers will always have latest version; revisions sent to arXiv only for major change
Can one factor the classical adjoint of a generic matrix?
can one factor the classical adjoint of a generic matrix?
integer generic i.e. indeterminates adjoint. char noninvertible restricted nontrivial factorizations occur. nonzero open. arises exterior functor modules posed operations arising revised answer version. answer buchweitz leuschke note. copy gbergman papers latest revisions sent
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2581364
10.1007/s00031-005-1107-4
We study a generalization of the isomonodromic deformation to the case of connections with irregular singularities. We call this generalization Isostokes Deformation. A new deformation parameter arises: one can deform the formal normal forms of connections at irregular points. We study this part of the deformation, giving an algebraic description. Then we show how to use loop groups and hypercohomology to write explicit hamiltonians. We work on an arbitrary complete algebraic curve, the structure group is an arbitrary semisimiple group.Comment: 23 pages, minor corrections in the introduction, references expande
Algebraic and hamiltonian approaches to isostokes deformations
algebraic and hamiltonian approaches to isostokes deformations
generalization isomonodromic deformation connections irregular singularities. call generalization isostokes deformation. deformation arises deform formal connections irregular points. deformation giving algebraic description. hypercohomology hamiltonians. algebraic semisimiple pages minor expande
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2584412
10.1007/s00031-005-1116-3
Let G be a complex reductive group. A normal G-variety X is called spherical if a Borel subgroup of G has a dense orbit in X. Of particular interest are spherical varieties which are smooth and affine since they form local models for multiplicity free Hamiltonian K-manifolds, K a maximal compact subgroup of G. In this paper, we classify all smooth affine spherical varieties up to coverings, central tori, and C*-fibrations.Comment: v1: 23 pages, uses texdraw; v2: 25 pages, introduction updated, Lemma 7.2 fixed, references added, typos correcte
Classification of smooth affine spherical varieties
classification of smooth affine spherical varieties
reductive group. spherical borel subgroup dense orbit spherical varieties affine multiplicity manifolds maximal subgroup classify affine spherical varieties coverings tori pages texdraw pages updated typos correcte
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36025335
10.1007/s00031-005-1124-3
34 pages.-- MSC codes: 53C30; 53C26.-- Printed version published Dec 2006.-- ArXiv pre-print available at: http://arxiv.org/abs/math/0504550An explicit classification of homogeneous quaternionic Kaehler structures by real tensors is derived and we relate this to the\ud representation-theoretic description found by Fino. We then show how the quaternionic hyperbolic space HH(n) is characterised by admitting homogeneous structures of a particularly simple type. In the process we\ud study the properties of different homogeneous models for HH(n).Partially supported by DGICYT, Spain, under Grant MTM2005-00173. Partially supported by the EDGE, Research Training Network HPRN-CT-2000-0010, of the European Human Potential Programme.Peer reviewe
Homogeneous quaternionic Kaehler structures and quaternionic hyperbolic space
homogeneous quaternionic kaehler structures and quaternionic hyperbolic space
pages. codes printed print homogeneous quaternionic kaehler tensors relate theoretic fino. quaternionic hyperbolic characterised admitting homogeneous type. homogeneous .partially dgicyt spain partially hprn programme.peer reviewe
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2593622
10.1007/s00031-005-1125-2
We study the composition of the functor from the category of modules over the Lie algebra gl_m to the category of modules over the degenerate affine Hecke algebra of GL_N introduced by I. Cherednik, with the functor from the latter category to the category of modules over the Yangian Y(gl_n) due to V. Drinfeld. We propose a representation theoretic explanation of a link between the intertwining operators on the tensor products of Y(gl_n)-modules, and the `extremal cocycle' on the Weyl group of gl_m defined by D. Zhelobenko. We also establish a connection between the composition of two functors, and the `centralizer construction' of the Yangian Y(gl_n) discovered by G. Olshanski.Comment: publication details added. arXiv admin note: substantial text overlap with arXiv:math/060627
Yangians and Mickelsson Algebras I
yangians and mickelsson algebras i
functor modules modules degenerate affine hecke cherednik functor modules yangian drinfeld. propose theoretic explanation intertwining modules extremal cocycle weyl zhelobenko. establish connection functors centralizer yangian discovered publication added. admin substantial overlap math
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2584917
10.1007/s00031-005-1127-0
Using methods applied by Atiyah in equivariant K-theory, Bredon obtained exact sequences for the relative cohomologies (with rational coefficients) of the equivariant skeletons of (sufficiently nice) T-spaces, T=(S^1)^n, with free equivariant cohomology over the cohomology of BT. Here we characterise those finite T-CW complexes with connected isotropy groups for which an analogous result holds with integral coefficients.Comment: similar main result as in our preprint math.AT/0307112, but the proof is more elementary; 10 pages; final versio
Exact cohomology sequences with integral coefficients for torus actions
exact cohomology sequences with integral coefficients for torus actions
atiyah equivariant bredon cohomologies rational equivariant skeletons sufficiently nice equivariant cohomology cohomology characterise complexes isotropy analogous preprint math.at elementary pages versio
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2588533
10.1007/s00031-006-0051-2
In two 1966 papers, Jacques Tits gave a construction of exceptional Lie algebras (hence implicitly exceptional algebraic groups) and a classification of possible indexes of simple algebraic groups. For the special case of his construction that gives groups of type E6, we connect the two papers by answering the question: Given an Albert algebra A and a separable quadratic field extension K, what is the index of the resulting algebraic group?Comment: 29 pages. For possibly newer versions, see http://www.mathcs.emory.edu/~skip/preprints.htm
Groups of outer type E6 with trivial Tits algebras
groups of outer type e6 with trivial tits algebras
papers jacques tits gave exceptional algebras implicitly exceptional algebraic indexes algebraic groups. connect papers answering albert separable quadratic algebraic comment pages. possibly newer versions skip preprints.htm
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2594159
10.1007/s00031-007-0057-4
A visible action on a complex manifold is a holomorphic action that admits a $J$-transversal totally real submanifold $S$. It is said to be strongly visible if there exists an orbit-preserving anti-holomorphic diffeomorphism $\sigma$ such that $\sigma |_S = \mathrm{id}$. In this paper, we prove that for any Hermitian symmetric space $D = G/K$ the action of any symmetric subgroup $H$ is strongly visible. The proof is carried out by finding explicitly an orbit-preserving anti-holomorphic involution and a totally real submanifold $S$. Our geometric results provide a uniform proof of various multiplicity-free theorems of irreducible highest weight modules when restricted to reductive symmetric pairs, for both classical and exceptional cases, for both finite and infinite dimensional cases, and for both discrete and continuous spectra
Visible actions on symmetric spaces
visible actions on symmetric spaces
visible manifold holomorphic admits transversal totally submanifold said visible orbit preserving holomorphic diffeomorphism sigma sigma mathrm hermitian subgroup visible. explicitly orbit preserving holomorphic involution totally submanifold geometric multiplicity theorems irreducible modules restricted reductive exceptional infinite
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2594528
10.1007/s00031-007-0061-8
We describe a stratification on the double flag variety $G/B^+\times G/B^-$ of a complex semisimple algebraic group $G$ analogous to the Deodhar stratification on the flag variety $G/B^+$, which is a refinement of the stratification into orbits both for $B^+\times B^-$ and for the diagonal action of $G$, just as Deodhar's stratification refines the orbits of $B^+$ and $B^-$. We give a coordinate system on each stratum, and show that all strata are coisotropic subvarieties. Also, we discuss possible connections to the positive and cluster geometry of $G/B^+\times G/B^-$, which would generalize results of Fomin and Zelevinsky on double Bruhat cells and Marsh and Rietsch on double Schubert cells.Comment: 21 page
A Deodhar type stratification on the double flag variety
a deodhar type stratification on the double flag variety
stratification flag semisimple algebraic analogous deodhar stratification flag refinement stratification orbits diagonal deodhar stratification refines orbits coordinate stratum strata coisotropic subvarieties. connections generalize fomin zelevinsky bruhat marsh rietsch schubert
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2598978
10.1007/s00031-008-9006-0
Our main result is that the simple Lie group $G=Sp(n,1)$ acts properly isometrically on $L^p(G)$ if $p>4n+2$. To prove this, we introduce property $({\BP}_0^V)$, for $V$ be a Banach space: a locally compact group $G$ has property $({\BP}_0^V)$ if every affine isometric action of $G$ on $V$, such that the linear part is a $C_0$-representation of $G$, either has a fixed point or is metrically proper. We prove that solvable groups, connected Lie groups, and linear algebraic groups over a local field of characteristic zero, have property $({\BP}_0^V)$. As a consequence for unitary representations, we characterize those groups in the latter classes for which the first cohomology with respect to the left regular representation on $L^2(G)$ is non-zero; and we characterize uniform lattices in those groups for which the first $L^2$-Betti number is non-zero.Comment: 28 page
Isometric group actions on Banach spaces and representations vanishing at infinity
isometric group actions on banach spaces and representations vanishing at infinity
acts properly isometrically banach locally affine isometric metrically proper. solvable algebraic unitary representations characterize cohomology characterize lattices betti
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1936728
10.1007/s00031-008-9009-x
We compute the integral cohomology of the minimal non-trivial nilpotent orbit in a complex simple (or quasi-simple) Lie algebra. We find by a uniform approach that the middle cohomology group is isomorphic to the fundamental group of the sub-root system generated by the long simple roots. The modulo $\ell$ reduction of the Springer correspondent representation involves the sign representation exactly when $\ell$ divides the order of this cohomology group. The primes dividing the torsion of the rest of the cohomology are bad primes.Comment: 29 pages, v2 : Leray-Serre spectral sequence replaced by Gysin sequence only, corrected typo
Cohomology of the minimal nilpotent orbit
cohomology of the minimal nilpotent orbit
cohomology trivial nilpotent orbit quasi algebra. cohomology isomorphic roots. modulo springer correspondent involves divides cohomology group. primes dividing torsion cohomology pages leray serre replaced gysin corrected typo
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1964029
10.1007/s00031-008-9037-6
We construct natural selfmaps of compact cohomgeneity one manifolds with finite Weyl group and compute their degrees and Lefschetz numbers. On manifolds with simple cohomology rings this yields in certain cases relations between the order of the Weyl group and the Euler characteristic of a principal orbit. We apply our construction to the compact Lie group SU(3) where we extend identity and transposition to an infinite family of selfmaps of every odd degree. The compositions of these selfmaps with the power maps realize all possible degrees of selfmaps of SU(3).Comment: v2, v3: minor improvement
Cohomogeneity one manifolds and selfmaps of nontrivial degree
cohomogeneity one manifolds and selfmaps of nontrivial degree
selfmaps cohomgeneity manifolds weyl lefschetz numbers. manifolds cohomology rings weyl euler principal orbit. extend transposition infinite selfmaps degree. compositions selfmaps realize selfmaps .comment minor
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2030240
10.1007/s00031-010-9089-2
Let X=spec A be a normal affine variety over an algebraically closed field k of characteristic 0 endowed with an effective action of a torus T of dimension n. Let also D be a homogeneous locally nilpotent derivation on the normal affine Z^n-graded domain A, so that D generates a k_+-action on X that is normalized by the T-action. We provide a complete classification of pairs (X,D) in two cases: for toric varieties (n=\dim X) and in the case where n=\dim X-1. This generalizes previously known results for surfaces due to Flenner and Zaidenberg. As an application we compute the homogeneous Makar-Limanov invariant of such varieties. In particular we exhibit a family of non-rational varieties with trivial Makar-Limanov invariant.Comment: 31 pages. Minor changes in the structure. Fixed some typo
Affine T-varieties of complexity one and locally nilpotent derivations
affine t-varieties of complexity one and locally nilpotent derivations
spec affine algebraically endowed torus homogeneous locally nilpotent derivation affine graded generates action. toric varieties generalizes flenner zaidenberg. homogeneous makar limanov varieties. exhibit rational varieties trivial makar limanov pages. minor structure. typo
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4434351
10.1007/s00031-010-9103-8
We compute the space of Poisson traces on a classical W-algebra, i.e., linear functionals invariant under Hamiltonian derivations. Modulo any central character, this space identifies with the top cohomology of the corresponding Springer fiber. As a consequence, we deduce that the zeroth Hochschild homology of the corresponding quantum W-algebra modulo a central character identifies with the top cohomology of the corresponding Springer fiber. This implies that the number of irreducible finite-dimensional representations of this algebra is bounded by the dimension of this top cohomology, which was established earlier by C. Dodd using reduction to positive characteristic. Finally, we prove that the entire cohomology of the Springer fiber identifies with the so-called Poisson-de Rham homology (defined previously by the authors) of the centrally reduced classical W-algebra.National Science Foundation (U.S.) (grant DMS-0504847)National Science Foundation (U.S.) (grant DMS-0900233
Traces on finite W-algebras
traces on finite w-algebras
poisson traces i.e. functionals derivations. modulo character identifies cohomology springer fiber. deduce zeroth hochschild homology modulo character identifies cohomology springer fiber. irreducible representations cohomology dodd characteristic. cohomology springer fiber identifies poisson rham homology centrally algebra.national foundation u.s. foundation u.s.
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2066655
10.1007/s00031-011-9120-2
Let G be a simply connected semisimple algebraic group over an algebraically closed field k of characteristic 0 and let V be a rational simple G-module of finite dimension. If G/H \subset P(V) is a spherical orbit and if X is its closure, then we describe the orbits of X and those of its normalization. If moreover the wonderful completion of G/H is strict, then we give necessary and sufficient combinatorial conditions so that the normalization morphism is a homeomorphism. Such conditions are trivially fulfilled if G is simply laced or if H is a symmetric subgroup.Comment: 24 pages, LaTeX. v4: Final version, to appear in Transformation Groups. Simplified some proofs and corrected minor mistakes, added references. v3: major changes due to a mistake in previous version
Spherical orbit closures in simple projective spaces and their normalizations
spherical orbit closures in simple projective spaces and their normalizations
semisimple algebraic algebraically rational module dimension. spherical orbit closure orbits normalization. wonderful completion strict combinatorial normalization morphism homeomorphism. trivially fulfilled laced pages latex. groups. simplified proofs corrected minor mistakes references. mistake
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2106249
10.1007/s00031-011-9127-8
We study a type of left-invariant structure on Lie groups, or equivalently on Lie algebras. We introduce obstructions to the existence of a hypo structure, namely the 5-dimensional geometry of hypersurfaces in manifolds with holonomy SU(3). The choice of a splitting g^*=V_1 + V_2, and the vanishing of certain associated cohomology groups, determine a first obstruction. We also construct necessary conditions for the existence of a hypo structure with a fixed almost-contact form. For non-unimodular Lie algebras, we derive an obstruction to the existence of a hypo structure, with no choice involved. We apply these methods to classify solvable Lie algebras that admit a hypo structure.Comment: 21 pages; v2: presentation improved, typos corrected, notational conflicts eliminated. To appear in Transformation Group
Solvable Lie algebras are not that hypo
solvable lie algebras are not that hypo
equivalently algebras. obstructions hypo hypersurfaces manifolds holonomy splitting vanishing cohomology obstruction. hypo form. unimodular algebras derive obstruction hypo involved. classify solvable algebras admit hypo pages presentation typos corrected notational conflicts eliminated.
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2104292
10.1007/s00031-011-9131-z
Automorphism groups of locally finite trees provide a large class of examples of simple totally disconnected locally compact groups. It is desirable to understand the connections between the global and local structure of such a group. Topologically, the local structure is given by the commensurability class of a vertex stabiliser; on the other hand, the action on the tree suggests that the local structure should correspond to the local action of a stabiliser of a vertex on its neighbours. We study the interplay between these different aspects for the special class of groups satisfying Tits' independence property. We show that such a group has few open subgroups if and only if it acts locally primitively. Moreover, we show that it always admits many germs of automorphisms which do not extend to automorphisms, from which we deduce a negative answer to a question by George Willis. Finally, under suitable assumptions, we compute the full group of germs of automorphisms; in some specific cases, these turn out to be simple and compactly generated, thereby providing a new infinite family of examples which generalise Neretin's group of spheromorphisms. Our methods describe more generally the abstract commensurator group for a large family of self-replicating profinite branch groups
Simple locally compact groups acting on trees and their germs of automorphisms
simple locally compact groups acting on trees and their germs of automorphisms
automorphism locally trees totally disconnected locally groups. desirable connections group. topologically commensurability stabiliser stabiliser neighbours. interplay satisfying tits independence property. subgroups acts locally primitively. admits germs automorphisms extend automorphisms deduce answer george willis. assumptions germs automorphisms compactly thereby infinite generalise neretin spheromorphisms. commensurator replicating profinite branch
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2189877
10.1007/s00031-011-9167-0
Given a holomorphic line bundle over the complex affine quadric $Q^2$, we investigate its Stein, SU(2)-equivariant disc bundles. Up to equivariant biholomorphism, these are all contained in a maximal one, say $\Omega_{max}$. By removing the zero section to $\Omega_{max}$ one obtains the unique Stein, SU(2)-equivariant, punctured disc bundle over $Q^2$ which contains entire curves. All other such punctured disc bundles are shown to be Kobayashi hyperbolic.Comment: 15 pages, v2: minor changes, to appear in Transformation Group
On hyperbolicity of SU(2)-equivariant, punctured disc bundles over the complex affine quadric
on hyperbolicity of su(2)-equivariant, punctured disc bundles over the complex affine quadric
holomorphic bundle affine quadric stein equivariant disc bundles. equivariant biholomorphism maximal omega removing omega obtains stein equivariant punctured disc bundle curves. punctured disc bundles kobayashi pages minor
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2180701
10.1007/s00031-012-9174-9
Geometric and dynamic properties of embeddings of SL(2,Z) into the Cremona group are studied. Infinitely many non-conjugate embeddings which preserve the type (i.e. which send elliptic, parabolic and hyperbolic elements onto elements of the same type) are provided. The existence of infinitely many non-conjugate elliptic, parabolic and hyperbolic embeddings is also shown. In particular, a group G of automorphisms of a smooth surface S obtained by blowing-up 10 points of the complex projective plane is given. The group G is isomorphic to SL(2,Z), preserves an elliptic curve and all its elements of infinite order are hyperbolic.Comment: to appear in Transformation Group
Embeddings of SL(2,Z) into the Cremona group
embeddings of sl(2,z) into the cremona group
geometric embeddings cremona studied. infinitely conjugate embeddings preserve i.e. send elliptic parabolic hyperbolic provided. infinitely conjugate elliptic parabolic hyperbolic embeddings shown. automorphisms blowing projective given. isomorphic preserves elliptic infinite
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2185113
10.1007/s00031-012-9176-7
We classify Nichols algebras of irreducible Yetter-Drinfeld modules over groups such that the underlying rack is braided and the homogeneous component of degree three of the Nichols algebra satisfies a given inequality. This assumption turns out to be equivalent to a factorization assumption on the Hilbert series. Besides the known Nichols algebras we obtain a new example. Our method is based on a combinatorial invariant of the Hurwitz orbits with respect to the action of the braid group on three strands.Comment: v2: 35 pages, 6 tables, 14 figure
Braided racks, Hurwitz actions and Nichols algebras with many cubic relations
braided racks, hurwitz actions and nichols algebras with many cubic relations
classify nichols algebras irreducible yetter drinfeld modules rack braided homogeneous nichols satisfies inequality. turns factorization hilbert series. besides nichols algebras example. combinatorial hurwitz orbits braid pages tables
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2136335
10.1007/s00031-012-9178-5
In the present paper we introduce and study the notion of an equivariant pretheory: basic examples include equivariant Chow groups, equivariant K-theory and equivariant algebraic cobordism. To extend this set of examples we define an equivariant (co)homology theory with coefficients in a Rost cycle module and provide a version of Merkurjev's (equivariant K-theory) spectral sequence for such a theory. As an application we generalize the theorem of Karpenko-Merkurjev on G-torsors and rational cycles; to every G-torsor E and a G-equivariant pretheory we associate a graded ring which serves as an invariant of E. In the case of Chow groups this ring encodes the information concerning the motivic J-invariant of E and in the case of Grothendieck's K_0 -- indexes of the respective Tits algebras.Comment: 23 pages; this is an essentially extended version of the previous preprint: the construction of an equivariant cycle (co)homology and the spectral sequence (generalizing the long exact localization sequence) are adde
Equivariant pretheories and invariants of torsors
equivariant pretheories and invariants of torsors
notion equivariant pretheory equivariant chow equivariant equivariant algebraic cobordism. extend equivariant homology rost module merkurjev equivariant theory. generalize karpenko merkurjev torsors rational cycles torsor equivariant pretheory associate graded serves chow encodes concerning motivic grothendieck indexes respective tits pages essentially preprint equivariant homology generalizing localization adde
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2136034
10.1007/s00031-012-9181-x
In this paper we study the structure of cohomology spaces for the Frobenius kernels of unipotent and parabolic algebraic group schemes and of their quantum analogs. Given a simple algebraic group $G$, a parabolic subgroup $P_J$, and its unipotent radical $U_J$, we determine the ring structure of the cohomology ring $H^\bullet((U_J)_1,k)$. We also obtain new results on computing $H^\bullet((P_J)_1,L(\lambda))$ as an $L_J$-module where $L(\lambda)$ is a simple $G$-module with high weight $\lambda$ in the closure of the bottom $p$-alcove. Finally, we provide generalizations of all our results to the quantum situation.Comment: 18 pages. Some proofs streamlined over previous version. Additional details added to some proofs in Section
Cohomology for infinitesimal unipotent algebraic and quantum groups
cohomology for infinitesimal unipotent algebraic and quantum groups
cohomology frobenius kernels unipotent parabolic algebraic schemes analogs. algebraic parabolic subgroup unipotent radical cohomology bullet bullet lambda module lambda module lambda closure alcove. generalizations pages. proofs streamlined version. proofs
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2187089
10.1007/s00031-012-9184-7
Let G be a simple algebraic group over an algebraically closed field of good odd characteristic, and let theta be an automorphism of G arising from an involution of its Dynkin diagram. We show that the spherical theta-twisted conjugacy classes are precisely those intersecting only Bruhat cells corresponding to twisted involutions in the Weyl group. We show how the analogue of this statement fails in the triality case. We generalize to good odd characteristic J-H. Lu's dimension formula for spherical twisted conjugacy classes.Comment: proof of Lemma 6.4 polished. The journal version is available at http://www.springerlink.com/content/k573l88256753640
On spherical twisted conjugacy classes
on spherical twisted conjugacy classes
algebraic algebraically theta automorphism arising involution dynkin diagram. spherical theta twisted conjugacy precisely intersecting bruhat twisted involutions weyl group. analogue statement fails triality case. generalize spherical twisted conjugacy polished.
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2255074
10.1007/s00031-012-9202-9
We discuss symplectic cutting for Hamiltonian actions of non-Abelian compact groups. By using a degeneration based on the Vinberg monoid we give, in good cases, a global quotient description of a surgery construction introduced by Woodward and Meinrenken, and show it can be interpreted in algebro-geometric terms. A key ingredient is the `universal cut' of the cotangent bundle of the group itself, which is identified with a moduli space of framed bundles on chains of projective lines recently introduced by the authors.Comment: Various edits made, to appear in Transformation Groups. 28 pages, 8 figure
On Non-Abelian Symplectic Cutting
on non-abelian symplectic cutting
symplectic cutting abelian groups. degeneration vinberg monoid quotient woodward meinrenken interpreted algebro geometric terms. ingredient universal cotangent bundle moduli framed bundles chains projective edits groups. pages
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6206769
10.1007/s00031-013-9221-1
We use equivariant localization and divided difference operators to determine formulas for the torus-equivariant fundamental cohomology classes of $K$-orbit closures on the flag variety $G/B$, where $G = GL(n,\C)$, and where $K$ is one of the symmetric subgroups $O(n,\C)$ or $Sp(n,\C)$. We realize these orbit closures as universal degeneracy loci for a vector bundle over a variety equipped with a single flag of subbundles and a nondegenerate symmetric or skew-symmetric bilinear form taking values in the trivial bundle. We describe how our equivariant formulas can be interpreted as giving formulas for the classes of such loci in terms of the Chern classes of the various bundles.Comment: Minor revisions and corrections suggested by referees. Final version, to appear in Transformation Group
K-orbit closures on G/B as universal degeneracy loci for flagged vector bundles with symmetric or skew-symmetric bilinear form
k-orbit closures on g/b as universal degeneracy loci for flagged vector bundles with symmetric or skew-symmetric bilinear form
equivariant localization divided formulas torus equivariant cohomology orbit closures flag subgroups realize orbit closures universal degeneracy loci bundle equipped flag subbundles nondegenerate skew bilinear trivial bundle. equivariant formulas interpreted giving formulas loci chern minor revisions referees.
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5255578
10.1007/s00031-013-9240-y
We construct and study a family of toric degenerations of the algebra of conformal blocks for a stable marked curve $(C, \vec{p})$ with structure group $SL_3(\mathbb{C}).$ We find that this algebra is Gorenstein. For the genus $0, 1$ cases we find the level of conformal blocks necessary to generate the algebra. In the genus 0 case we also find bounds on the degrees of relations required to present the algebra. Along the way we recover polyhedral rules for counting conformal blocks originally due to Senechal, Mathieu, Kirillov, and Walton.Comment: 22 pages, 13 figure
The algebra of $SL_3(\mathbb{C})$ conformal blocks
the algebra of $sl_3(\mathbb{c})$ conformal blocks
toric degenerations conformal blocks marked mathbb gorenstein. genus conformal blocks algebra. genus bounds algebra. recover polyhedral counting conformal blocks originally senechal mathieu kirillov pages
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51959792
10.1007/s00031-014-9253-1
International audienceLet $W$ be a finite-dimensional representation of a reductive algebraic group $G$. The invariant Hilbert scheme $\mathcal{H}$ is a moduli space that classifies the $G$-stable closed subschemes $Z$ of $W$ such that the affine algebra $k[Z]$ is the direct sum of simple $G$-modules with prescribed multiplicities. In this article, we consider the case where $G$ is a classical group acting on a classical representation $W$ and $k[Z]$ is isomorphic to the regular representation of $G$ as a $G$-module. We obtain families of examples where $\mathcal{H}$ is a smooth variety, and thus for which the Hilbert-Chow morphism $\gamma: \mathcal{H} \rightarrow W//G$ is a canonical desingularization of the categorical quotient
Invariant Hilbert schemes and desingularizations of quotients by classical groups
invariant hilbert schemes and desingularizations of quotients by classical groups
audiencelet reductive algebraic hilbert mathcal moduli classifies subschemes affine modules prescribed multiplicities. acting isomorphic module. families mathcal hilbert chow morphism gamma mathcal rightarrow canonical desingularization categorical quotient
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78058183
10.1007/s00031-014-9260-2
P. Deligne defined interpolations of the tensor category of representations of the symmetric group S [subscript n] to complex values of n. Namely, he defined tensor categories Rep(S [subscript t]) for any complex t. This construction was generalized by F. Knop to the case of wreath products of S[subscript n] with a finite group. Generalizing these results, we propose a method of interpolating representation categories of various algebras containing S [subscript n] (such as degenerate affine Hecke algebras, symplectic reflection algebras, rational Cherednik algebras, etc.) to complex values of n. We also define the group algebra of S [subscript n] for complex n, study its properties, and propose a Schur-Weyl duality for Rep(S [subscript t]).National Science Foundation (U.S.) (Grant DMS-0504847)National Science Foundation (U.S.) (Grant DMS-1000113
Representation Theory in Complex Rank, I
representation theory in complex rank, i
deligne interpolations representations subscript categories subscript knop wreath subscript group. generalizing propose interpolating categories algebras subscript degenerate affine hecke algebras symplectic reflection algebras rational cherednik algebras etc. subscript propose schur weyl duality subscript .national foundation u.s. foundation u.s.
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83228173
10.1007/s00031-014-9263-z
We show that the normalized supercharacters of principal admissible modules over the affine Lie superalgebra sℓˆ[subscript 2|1] (resp. psℓˆ[subscript 2|2]) can be modified, using Zwegers’ real analytic corrections, to form a modular (resp. S-) invariant family of functions. Applying the quantum Hamiltonian reduction, this leads to a new family of positive energy modules over the N = 2 (resp.N = 4) superconformal algebras with central charge 3(1 − (2 m + 2)/M), where m ∈ ℤ[subscript ≥0], M ∈ ℤ[subscript ≥2], gcd(2 m + 2, M) = 1 if m > 0 (resp. 6 (m/M − 1), where m ∈ ℤ[subscript ≥1], M ∈ ℤ[subscript ≥2], gcd(2 m, M) = 1 if m > 1), whose modified characters and supercharacters form a modular invariant family
REPRESENTATIONS OF AFFINE SUPERALGEBRAS AND MOCK THETA FUNCTIONS
representations of affine superalgebras and mock theta functions
supercharacters principal admissible modules affine superalgebra subscript resp. psℓˆ subscript zwegers’ analytic modular resp. functions. modules resp.n superconformal algebras subscript subscript resp. subscript subscript characters supercharacters modular
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