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regularities of the distribution of abstract van der corput sequences

0809.3994

similarly to $\beta$-adic van der corput sequences, abstract van der corputsequences can be defined for abstract numeration systems. under someassumptions, these sequences are low discrepancy sequences. the discrepancyfunction is computed explicitely, and a characterization of bounded remaindersets of the form $[0,y)$ is provided.

math.nt cs.dm

nan

['steiner']

https://arxiv.org/abs/0809.3994

modelling interdependencies between the electricity and information infrastructures

0809.4107

the aim of this paper is to provide qualitative models characterizinginterdependencies related failures of two critical infrastructures: theelectricity infrastructure and the associated information infrastructure. theinterdependencies of these two infrastructures are increasing due to a growingconnection of the power grid networks to the global information infrastructure,as a consequence of market deregulation and opening. these interdependenciesincrease the risk of failures. we focus on cascading, escalating andcommon-cause failures, which correspond to the main causes of failures due tointerdependencies. we address failures in the electricity infrastructure, incombination with accidental failures in the information infrastructure, then weshow briefly how malicious attacks in the information infrastructure can beaddressed.

cs.dc

nan

['laprie', 'kanoun', 'kaaniche']

https://arxiv.org/abs/0809.4107

3d mimo scheme for broadcasting future digital tv in single frequency networks

0809.5145

this letter introduces a 3d space-time-space block code for future digital tvsystems. the code is based on a double layer structure for inter-cell andintra-cell transmission mode in single frequency networks. without increasingthe complexity of the receiver, the proposed code is very efficient fordifferent transmission scenarios.

cs.ni

nan

['nasser', 'hélard', 'crussière']

https://arxiv.org/abs/0809.5145

a coded bit-loading linear precoded discrete multitone solution for power line communication

0809.5191

linear precoded discrete multitone modulation (lp-dmt) system has beenalready proved advantageous with adaptive resource allocation algorithm in apower line communication (plc) context. in this paper, we investigate the bitand energy allocation algorithm of an adaptive lp-dmt system taking intoaccount the channel coding scheme. a coded adaptive lp-dmt system is presentedin the plc context with a loading algorithm which ccommodates the channelcoding gains in bit and energy calculations. the performance of a concatenatedchannel coding scheme, consisting of an inner wei's 4-dimensional 16-statestrellis code and an outer reed-solomon code, in combination with the roposedalgorithm is analyzed. simulation results are presented for a fixed target biterror rate in a multicarrier scenario under power spectral density constraint.using a multipath model of plc channel, it is shown that the proposed codedadaptive lp-dmt system performs better than classical coded discrete multitone.

cs.it math.it

10.1109/spawc.2008.4641669

['muhammad', 'baudais', 'hélard', 'crussière']

https://arxiv.org/abs/0809.5191

coded adaptive linear precoded discrete multitone over plc channel

0809.5275

discrete multitone modulation (dmt) systems exploit the capabilities oforthogonal subcarriers to cope efficiently with narrowband interference, highfrequency attenuations and multipath fadings with the help of simpleequalization filters. adaptive linear precoded discrete multitone (lp-dmt)system is based on classical dmt, combined with a linear precoding component.in this paper, we investigate the bit and energy allocation algorithm of anadaptive lp-dmt system taking into account the channel coding scheme. a codedadaptive lpdmt system is presented in the power line communication (plc)context with a loading algorithm which accommodates the channel coding gains inbit and energy calculations. the performance of a concatenated channel codingscheme, consisting of an inner wei's 4-dimensional 16-states trellis code andan outer reed-solomon code, in combination with the proposed algorithm isanalyzed. theoretical coding gains are derived and simulation results arepresented for a fixed target bit error rate in a multicarrier scenario underpower spectral density constraint. using a multipath model of plc channel, itis shown that the proposed coded adaptive lp-dmt system performs better thancoded dmt and can achieve higher throughput for plc applications.

cs.it math.it

10.1109/isplc.2008.4510410

['muhammad', 'baudais', 'hélard', 'crussière']

https://arxiv.org/abs/0809.5275

cognitive radio with partial channel state information at the transmitter

0810.0870

in this paper, we present the cognitive radio system design with partialchannel state information known at the transmitter (csit).we replace the dirtypaper coding (dpc) used in the cognitive radio with full csit by the linearassignment gel'fand-pinsker coding (la-gpc), which can utilize the limitedknowledge of the channel more efficiently. based on the achievable rate derivedfrom the la-gpc, two optimization problems under the fast and slow fadingchannels are formulated. we derive semianalytical solutions to find therelaying ratios and precoding coefficients. the critical observation is thatthe complex rate functions in these problems are closely related to ratios ofquadratic form. simulation results show that the proposed semi-analyticalsolutions perform close to the optimal solutions found by brute-force search,and outperform the systems based on naive dpc. asymptotic analysis also showsthat these solutions converge to the optimal ones solved with full csit whenthe k-factor of rician channel approaches infinity. moreover, a new codingscheme is proposed to implement the la-gpc in practice. simulation results showthat the proposed practical coding scheme can efficiently reach the theoreticalrate performance.

cs.it math.it

10.1109/twc.2010.092410.090725

['lin', 'lin', 'lee', 'su']

https://arxiv.org/abs/0810.0870

a linear time algorithm for l(2,1)-labeling of trees

0810.0906

an l(2,1)-labeling of a graph $g$ is an assignment $f$ from the vertex set$v(g)$ to the set of nonnegative integers such that $|f(x)-f(y)|\ge 2$ if $x$and $y$ are adjacent and $|f(x)-f(y)|\ge 1$ if $x$ and $y$ are at distance 2,for all $x$ and $y$ in $v(g)$. a $k$-l(2,1)-labeling is an assignment$f:v(g)\to\{0,..., k\}$, and the l(2,1)-labeling problem asks the minimum $k$,which we denote by $\lambda(g)$, among all possible assignments. it is knownthat this problem is np-hard even for graphs of treewidth 2, and tree is one ofa very few classes for which the problem is polynomially solvable. the runningtime of the best known algorithm for trees had been $\mo(\delta^{4.5} n)$ formore than a decade, however, an $\mo(n^{1.75})$-time algorithm has beenproposed recently, which substantially improved the previous one, where$\delta$ is the maximum degree of $t$ and $n=|v(t)|$. in this paper, we finallyestablish a linear time algorithm for l(2,1)-labeling of trees.

cs.ds

nan

['hasunuma', 'ishii', 'ono', 'uno']

https://arxiv.org/abs/0810.0906

bi-directional half-duplex protocols with multiple relays

0810.1268

in a bi-directional relay channel, two nodes wish to exchange independentmessages over a shared wireless half-duplex channel with the help of relays.recent work has considered information theoretic limits of the bi-directionalrelay channel with a single relay. in this work we consider bi-directionalrelaying with multiple relays. we derive achievable rate regions and outerbounds for half-duplex protocols with multiple decode and forward relays andcompare these to the same protocols with amplify and forward relays in anadditive white gaussian noise channel. we consider three novel classes ofhalf-duplex protocols: the (m,2) 2 phase protocol with m relays, the (m,3) 3phase protocol with m relays, and general (m, t) multiple hops and multiplerelays (mhmr) protocols, where m is the total number of relays and 3<t< m+3 isthe number of temporal phases in the protocol. the (m,2) and (m,3) protocolsextend previous bi-directional relaying protocols for a single m=1 relay, whilethe new (m,t) protocol efficiently combines multi-hop routing withmessage-level network coding. finally, we provide a comprehensive treatment ofthe mhmr protocols with decode and forward relaying and amplify and forwardrelaying in the gaussian noise, obtaining their respective achievable rateregions, outer bounds and relative performance under different snrs and relaygeometries, including an analytical comparison on the protocols at low and highsnr.

cs.it math.it

nan

['kim', 'devroye', 'tarokh']

https://arxiv.org/abs/0810.1268

an analytical model of information dissemination for a gossip-based protocol

0810.1571

we develop an analytical model of information dissemination for a gossipingprotocol that combines both pull and push approaches. with this model weanalyse how fast an item is replicated through a network, and how fast the itemspreads in the network, and how fast the item covers the network. we alsodetermine the optimal size of the exchange buffer, to obtain fast replication.our results are confirmed by large-scale simulation experiments.

cs.dc cs.dm cs.it cs.pf math.it

10.1016/j.comnet.2009.03.017

['bakhshi', 'gavidia', 'fokkink', 'van steen']

https://arxiv.org/abs/0810.1571

on finite functions with non-trivial arity gap

0810.2279

given an $n$-ary $k-$valued function $f$, $gap(f)$ denotes the minimal number of essentialvariables in $f$ which become fictive when identifying any two distinctessential variables in $f$. we particularly solve a problem concerning the explicit determination of$n$-ary $k-$valued functions $f$ with $2\leq gap(f)\leq n\leq k$. our methods yieldnew combinatorial results about the number of such functions.

cs.dm cs.cc

nan

['shtrakov', 'koppitz']

https://arxiv.org/abs/0810.2279

a mordell inequality for lattices over maximal orders

0810.2336

in this paper we prove an analogue of mordell's inequality for lattices infinite-dimensional complex or quaternionic hermitian space that are modulesover a maximal order in an imaginary quadratic number field or a totallydefinite rational quaternion algebra. this inequality implies that the16-dimensional barnes-wall lattice has optimal density among all 16-dimensionallattices with hurwitz structures.

math.mg cs.it math.it math.nt

nan

['vance']

https://arxiv.org/abs/0810.2336

faster and better: a machine learning approach to corner detection

0810.2434

the repeatability and efficiency of a corner detector determines how likelyit is to be useful in a real-world application. the repeatability is importandbecause the same scene viewed from different positions should yield featureswhich correspond to the same real-world 3d locations [schmid et al 2000]. theefficiency is important because this determines whether the detector combinedwith further processing can operate at frame rate. three advances are described in this paper. first, we present a new heuristicfor feature detection, and using machine learning we derive a feature detectorfrom this which can fully process live pal video using less than 5% of theavailable processing time. by comparison, most other detectors cannot evenoperate at frame rate (harris detector 115%, sift 195%). second, we generalizethe detector, allowing it to be optimized for repeatability, with little lossof efficiency. third, we carry out a rigorous comparison of corner detectorsbased on the above repeatability criterion applied to 3d scenes. we show thatdespite being principally constructed for speed, on these stringent tests, ourheuristic detector significantly outperforms existing feature detectors.finally, the comparison demonstrates that using machine learning producessignificant improvements in repeatability, yielding a detector that is bothvery fast and very high quality.

cs.cv cs.lg

10.1109/tpami.2008.275

['rosten', 'porter', 'drummond']

https://arxiv.org/abs/0810.2434

a minimum relative entropy principle for learning and acting

0810.3605

this paper proposes a method to construct an adaptive agent that is universalwith respect to a given class of experts, where each expert is an agent thathas been designed specifically for a particular environment. this adaptivecontrol problem is formalized as the problem of minimizing the relative entropyof the adaptive agent from the expert that is most suitable for the unknownenvironment. if the agent is a passive observer, then the optimal solution isthe well-known bayesian predictor. however, if the agent is active, then itspast actions need to be treated as causal interventions on the i/o streamrather than normal probability conditions. here it is shown that the solutionto this new variational problem is given by a stochastic controller called thebayesian control rule, which implements adaptive behavior as a mixture ofexperts. furthermore, it is shown that under mild assumptions, the bayesiancontrol rule converges to the control law of the most suitable expert.

cs.ai cs.lg

nan

['ortega', 'braun']

https://arxiv.org/abs/0810.3605

optimal codes in deletion and insertion metric

0810.3729

we improve the upper bound of levenshtein for the cardinality of a code oflength 4 capable of correcting single deletions over an alphabet of even size.we also illustrate that the new upper bound is sharp. furthermore we willconstruct an optimal perfect code capable of correcting single deletions forthe same parameters.

cs.it cs.dm math.co math.it

nan

['kim', 'lee', 'oh']

https://arxiv.org/abs/0810.3729

directed transmission method, a fully asynchronous approach to solve sparse linear systems in parallel

0810.3783

in this paper, we propose a new distributed algorithm, called directedtransmission method (dtm). dtm is a fully asynchronous and continuous-timeiterative algorithm to solve spd sparse linear system. as an architecture-awarealgorithm, dtm could be freely running on all kinds of heterogeneous parallelcomputer. we proved that dtm is convergent by making use of the final-valuetheorem of laplacian transformation. numerical experiments show that dtm isstable and efficient.

math.na cs.dc

10.1145/1378533.1378598

['wei', 'yang']

https://arxiv.org/abs/0810.3783

best-effort group service in dynamic networks

0810.3836

we propose a group membership service for dynamic ad hoc networks. itmaintains as long as possible the existing groups and ensures that each groupdiameter is always smaller than a constant, fixed according to the applicationusing the groups. the proposed protocol is self-stabilizing and works indynamic distributed systems. moreover, it ensures a kind of continuity in theservice offer to the application while the system is converging, except if toostrong topology changes happen. such a best effort behavior allows applicationsto rely on the groups while the stabilization has not been reached, which isvery useful in dynamic ad hoc networks.

cs.dc

nan

['ducourthial', 'khalfallah', 'petit']

https://arxiv.org/abs/0810.3836

sums of residues on algebraic surfaces and application to coding theory

0810.4112

in this paper, we study residues of differential 2-forms on a smoothalgebraic surface over an arbitrary field and give several statements aboutsums of residues. afterwards, using these results we constructalgebraic-geometric codes which are an extension to surfaces of the well-knowndifferential codes on curves. we also study some properties of these codes andextend to them some known properties for codes on curves.

math.ag cs.it math.it

nan

['couvreur']

https://arxiv.org/abs/0810.4112

bicycle cycles and mobility patterns - exploring and characterizing data from a community bicycle program

0810.4187

this paper provides an analysis of human mobility data in an urban area usingthe amount of available bikes in the stations of the community bicycle programbicing in barcelona. the data was obtained by periodic mining of a kml-fileaccessible through the bicing website. although in principle very noisy, aftersome preprocessing and filtering steps the data allows to detect temporalpatterns in mobility as well as identify residential, university, business andleisure areas of the city. the results lead to a proposal for an improvement ofthe bicing website, including a prediction of the number of available bikes ina certain station within the next minutes/hours. furthermore a model foridentifying the most probable routes between stations is briefly sketched.

cs.cy cs.hc

nan

['kaltenbrunner', 'meza', 'grivolla', 'codina', 'banchs']

https://arxiv.org/abs/0810.4187

camera distortion self-calibration using the plumb-line constraint and minimal hough entropy

0810.4426

in this paper we present a simple and robust method for self-correction ofcamera distortion using single images of scenes which contain straight lines.since the most common distortion can be modelled as radial distortion, weillustrate the method using the harris radial distortion model, but the methodis applicable to any distortion model. the method is based on transforming theedgels of the distorted image to a 1-d angular hough space, and optimizing thedistortion correction parameters which minimize the entropy of thecorresponding normalized histogram. properly corrected imagery will have fewercurved lines, and therefore less spread in hough space. since the method doesnot rely on any image structure beyond the existence of edgels sharing somecommon orientations and does not use edge fitting, it is applicable to a widevariety of image types. for instance, it can be applied equally well to imagesof texture with weak but dominant orientations, or images with strong vanishingpoints. finally, the method is performed on both synthetic and real datarevealing that it is particularly robust to noise.

cs.cv

10.1007/s00138-009-0196-9

['rosten', 'loveland']

https://arxiv.org/abs/0810.4426

relating web pages to enable information-gathering tasks

0810.5428

we argue that relationships between web pages are functions of the user'sintent. we identify a class of web tasks - information-gathering - that can befacilitated by a search engine that provides links to pages which are relatedto the page the user is currently viewing. we define three kinds of intentionalrelationships that correspond to whether the user is a) seeking sources ofinformation, b) reading pages which provide information, or c) surfing throughpages as part of an extended information-gathering process. we show that thesethree relationships can be productively mined using a combination of textualand link information and provide three scoring mechanisms that correspond tothem: {\em seekrel}, {\em factrel} and {\em surfrel}. these scoring mechanismsincorporate both textual and link information. we build a set of capacitatedsubnetworks - each corresponding to a particular keyword - that mirror theinterconnection structure of the world wide web. the scores are computed bycomputing flows on these subnetworks. the capacities of the links are derivedfrom the {\em hub} and {\em authority} values of the nodes they connect,following the work of kleinberg (1998) on assigning authority to pages inhyperlinked environments. we evaluated our scoring mechanism by runningexperiments on four data sets taken from the web. we present user evaluationsof the relevance of the top results returned by our scoring mechanisms andcompare those to the top results returned by google's similar pages feature,and the {\em companion} algorithm proposed by dean and henzinger (1999).

cs.ir cs.ds

nan

['bagchi', 'lahoti']

https://arxiv.org/abs/0810.5428

model checking memoryful linear-time logics over one-counter automata

0810.5517

we study complexity of the model-checking problems for ltl with registers(also known as freeze ltl) and for first-order logic with data equality testsover one-counter automata. we consider several classes of one-counter automata(mainly deterministic vs. nondeterministic) and several logical fragments(restriction on the number of registers or variables and on the use ofpropositional variables for control locations). the logics have the ability tostore a counter value and to test it later against the current counter value.we show that model checking over deterministic one-counter automata ispspace-complete with infinite and finite accepting runs. by constrast, we provethat model checking freeze ltl in which the until operator is restricted to theeventually operator over nondeterministic one-counter automata is undecidableeven if only one register is used and with no propositional variable. as acorollary of our proof, this also holds for first-order logic with dataequality tests restricted to two variables. this makes a difference with thefacts that several verification problems for one-counter automata are known tobe decidable with relatively low complexity, and that finitary satisfiabilityfor the two logics are decidable. our results pave the way for model-checkingmemoryful (linear-time) logics over other classes of operational models, suchas reversal-bounded counter machines.

cs.lo

nan

['demri', 'lazic', 'sangnier']

https://arxiv.org/abs/0810.5517

effective complexity and its relation to logical depth

0810.5663

effective complexity measures the information content of the regularities ofan object. it has been introduced by m. gell-mann and s. lloyd to avoid some ofthe disadvantages of kolmogorov complexity, also known as algorithmicinformation content. in this paper, we give a precise formal definition ofeffective complexity and rigorous proofs of its basic properties. inparticular, we show that incompressible binary strings are effectively simple,and we prove the existence of strings that have effective complexity close totheir lengths. furthermore, we show that effective complexity is related tobennett's logical depth: if the effective complexity of a string $x$ exceeds acertain explicit threshold then that string must have astronomically largedepth; otherwise, the depth can be arbitrarily small.

cs.it math.it

10.1109/tit.2010.2053892

['ay', 'mueller', 'szkola']

https://arxiv.org/abs/0810.5663

interpolation of shifted-lacunary polynomials

0810.5685

given a "black box" function to evaluate an unknown rational polynomial f inq[x] at points modulo a prime p, we exhibit algorithms to compute therepresentation of the polynomial in the sparsest shifted power basis. that is,we determine the sparsity t, the shift s (a rational), the exponents 0 <= e1 <e2 < ... < et, and the coefficients c1,...,ct in q\{0} such that f(x) =c1(x-s)^e1+c2(x-s)^e2+...+ct(x-s)^et. the computed sparsity t is absolutelyminimal over any shifted power basis. the novelty of our algorithm is that thecomplexity is polynomial in the (sparse) representation size, and in particularis logarithmic in deg(f). our method combines previous celebrated results onsparse interpolation and computing sparsest shifts, and provides a way tohandle polynomials with extremely high degree which are, in some sense, sparsein information.

cs.sc cs.ds cs.ms

10.1007/s00037-010-0294-0

['giesbrecht', 'roche']

https://arxiv.org/abs/0810.5685

a complexity dichotomy for hypergraph partition functions

0811.0037

we consider the complexity of counting homomorphisms from an $r$-uniformhypergraph $g$ to a symmetric $r$-ary relation $h$. we give a dichotomy theoremfor $r>2$, showing for which $h$ this problem is in fp and for which $h$ it is#p-complete. this generalises a theorem of dyer and greenhill (2000) for thecase $r=2$, which corresponds to counting graph homomorphisms. our dichotomytheorem extends to the case in which the relation $h$ is weighted, and the goalis to compute the \emph{partition function}, which is the sum of weights of thehomomorphisms. this problem is motivated by statistical physics, where itarises as computing the partition function for particle models in which certaincombinations of $r$ sites interact symmetrically. in the weighted case, ourdichotomy theorem generalises a result of bulatov and grohe (2005) for graphs,where $r=2$. when $r=2$, the polynomial time cases of the dichotomy correspondsimply to rank-1 weights. surprisingly, for all $r>2$ the polynomial time casesof the dichotomy have rather more structure. it turns out that the weights mustbe superimposed on a combinatorial structure defined by solutions of anequation over an abelian group. our result also gives a dichotomy for a closelyrelated constraint satisfaction problem.

cs.cc cs.dm

nan

['dyer', 'goldberg', 'jerrum']

https://arxiv.org/abs/0811.0037

embedding non-ground logic programs into autoepistemic logic for knowledge base combination

0811.0359

in the context of the semantic web, several approaches to the combination ofontologies, given in terms of theories of classical first-order logic and rulebases, have been proposed. they either cast rules into classical logic or limitthe interaction between rules and ontologies. autoepistemic logic (ael) is anattractive formalism which allows to overcome these limitations, by serving asa uniform host language to embed ontologies and nonmonotonic logic programsinto it. for the latter, so far only the propositional setting has beenconsidered. in this paper, we present three embeddings of normal and threeembeddings of disjunctive non-ground logic programs under the stable modelsemantics into first-order ael. while the embeddings all correspond withrespect to objective ground atoms, differences arise when consideringnon-atomic formulas and combinations with first-order theories. we compare theembeddings with respect to stable expansions and autoepistemic consequences,considering the embeddings by themselves, as well as combinations withclassical theories. our results reveal differences and correspondences of theembeddings and provide useful guidance in the choice of a particular embeddingfor knowledge combination.

cs.lo cs.ai

nan

['de bruijn', 'eiter', 'polleres', 'tompits']

https://arxiv.org/abs/0811.0359

on the dynamics of social balance on general networks (with an application to xor-sat)

0811.0381

we study nondeterministic and probabilistic versions of a discrete dynamicalsystem (due to t. antal, p. l. krapivsky, and s. redner) inspired by heider'ssocial balance theory. we investigate the convergence time of this dynamics onseveral classes of graphs. our contributions include: 1. we point out the connection between the triad dynamics and ageneralization of annihilating walks to hypergraphs. in particular, thisconnection allows us to completely characterize the recurrent states in graphswhere each edge belongs to at most two triangles. 2. we also solve the case of hypergraphs that do not contain edges consistingof one or two vertices. 3. we show that on the so-called "triadic cycle" graph, the convergence timeis linear. 4. we obtain a cubic upper bound on the convergence time on 2-regular triadicsimplexes g. this bound can be further improved to a quantity that depends onthe cheeger constant of g. in particular this provides some rigorouscounterparts to previous experimental observations. we also point out an application to the analysis of the random walk algorithmon certain instances of the 3-xor-sat problem.

cs.dm math.co math.pr physics.soc-ph

nan

['istrate']

https://arxiv.org/abs/0811.0381

non-classical role of potential energy in adiabatic quantum annealing

0811.0881

adiabatic quantum annealing is a paradigm of analog quantum computation,where a given computational job is converted to the task of finding the globalminimum of some classical potential energy function and the search for theglobal potential minimum is performed by employing external kinetic quantumfluctuations and subsequent slow reduction (annealing) of them. in this method,the entire potential energy landscape (pel) may be accessed simultaneouslythrough a delocalized wave-function, in contrast to a classical search, wherethe searcher has to visit different points in the landscape (i.e., individualclassical configurations) sequentially. thus in such searches, the role of thepotential energy might be significantly different in the two cases. here wediscuss this in the context of searching of a single isolated hole (potentialminimum) in a golf-course type gradient free pel. we show, that the quantumparticle would be able to locate the hole faster if the hole is deeper, whilethe classical particle of course would have no scope to exploit the depth ofthe hole. we also discuss the effect of the underlying quantum phase transitionon the adiabatic dynamics.

quant-ph cond-mat.stat-mech cs.cc physics.comp-ph

10.1088/1742-6596/143/1/012001

['das']

https://arxiv.org/abs/0811.0881

the complexity of propositional implication

0811.0959

the question whether a set of formulae g implies a formula f is fundamental.the present paper studies the complexity of the above implication problem forpropositional formulae that are built from a systematically restricted set ofboolean connectives. we give a complete complexity classification for all setsof boolean functions in the meaning of post's lattice and show that theimplication problem is efficentily solvable only if the connectives aredefinable using the constants {false,true} and only one of {and,or,xor}. theproblem remains conp-complete in all other cases. we also consider therestriction of g to singletons.

cs.cc cs.lo

10.1016/j.ipl.2009.06.015

['beyersdorff', 'meier', 'thomas', 'vollmer']

https://arxiv.org/abs/0811.0959

modeling social annotation: a bayesian approach

0811.1319

collaborative tagging systems, such as delicious, citeulike, and others,allow users to annotate resources, e.g., web pages or scientific papers, withdescriptive labels called tags. the social annotations contributed by thousandsof users, can potentially be used to infer categorical knowledge, classifydocuments or recommend new relevant information. traditional text inferencemethods do not make best use of social annotation, since they do not take intoaccount variations in individual users' perspectives and vocabulary. in aprevious work, we introduced a simple probabilistic model that takes interestsof individual annotators into account in order to find hidden topics ofannotated resources. unfortunately, that approach had one major shortcoming:the number of topics and interests must be specified a priori. to address thisdrawback, we extend the model to a fully bayesian framework, which offers a wayto automatically estimate these numbers. in particular, the model allows thenumber of interests and topics to change as suggested by the structure of thedata. we evaluate the proposed model in detail on the synthetic and real-worlddata by comparing its performance to latent dirichlet allocation on the topicextraction task. for the latter evaluation, we apply the model to infer topicsof web resources from social annotations obtained from delicious in order todiscover new resources similar to a specified one. our empirical resultsdemonstrate that the proposed model is a promising method for exploiting socialknowledge contained in user-generated annotations.

cs.ai

nan

['plangprasopchok', 'lerman']

https://arxiv.org/abs/0811.1319

on the long time behavior of the tcp window size process

0811.2180

the tcp window size process appears in the modeling of the famoustransmission control protocol used for data transmission over the internet.this continuous time markov process takes its values in $[0,\infty)$, isergodic and irreversible. it belongs to the additive increase multiplicativedecrease class of processes. the sample paths are piecewise lineardeterministic and the whole randomness of the dynamics comes from the jumpmechanism. several aspects of this process have already been investigated inthe literature. in the present paper, we mainly get quantitative estimates forthe convergence to equilibrium, in terms of the $w_1$ wasserstein couplingdistance, for the process and also for its embedded chain.

math.pr cs.ni

10.1016/j.spa.2010.03.019

['chafai', 'malrieu', 'paroux']

https://arxiv.org/abs/0811.2180

computing voting power in easy weighted voting games

0811.2497

weighted voting games are ubiquitous mathematical models which are used ineconomics, political science, neuroscience, threshold logic, reliability theoryand distributed systems. they model situations where agents with variablevoting weight vote in favour of or against a decision. a coalition of agents iswinning if and only if the sum of weights of the coalition exceeds or equals aspecified quota. the banzhaf index is a measure of voting power of an agent ina weighted voting game. it depends on the number of coalitions in which theagent is the difference in the coalition winning or losing. it is well knownthat computing banzhaf indices in a weighted voting game is np-hard. we give acomprehensive classification of weighted voting games which can be solved inpolynomial time. among other results, we provide a polynomial($o(k{(\frac{n}{k})}^k)$) algorithm to compute the banzhaf indices in weightedvoting games in which the number of weight values is bounded by $k$.

cs.gt cs.cc cs.ds

nan

['aziz', 'paterson']

https://arxiv.org/abs/0811.2497

an efficient algorithm for partial order production

0811.2572

we consider the problem of partial order production: arrange the elements ofan unknown totally ordered set t into a target partially ordered set s, bycomparing a minimum number of pairs in t. special cases include sorting bycomparisons, selection, multiple selection, and heap construction. we give an algorithm performing itlb + o(itlb) + o(n) comparisons in theworst case. here, n denotes the size of the ground sets, and itlb denotes anatural information-theoretic lower bound on the number of comparisons neededto produce the target partial order. our approach is to replace the target partial order by a weak order (that is,a partial order with a layered structure) extending it, without increasing theinformation theoretic lower bound too much. we then solve the problem byapplying an efficient multiple selection algorithm. the overall complexity ofour algorithm is polynomial. this answers a question of yao (siam j. comput.18, 1989). we base our analysis on the entropy of the target partial order, a quantitythat can be efficiently computed and provides a good estimate of theinformation-theoretic lower bound.

cs.ds

10.1137/090759860

['cardinal', 'fiorini', 'joret', 'jungers', 'munro']

https://arxiv.org/abs/0811.2572

ag codes from polyhedral divisors

0811.2696

a description of complete normal varieties with lower dimensional torusaction has been given by altmann, hausen, and suess, generalizing the theory oftoric varieties. considering the case where the acting torus t has codimensionone, we describe t-invariant weil and cartier divisors and provide formulae forcalculating global sections, intersection numbers, and euler characteristics.as an application, we use divisors on these so-called t-varieties to define newevaluation codes called t-codes. we find estimates on their minimum distanceusing intersection theory. this generalizes the theory of toric codes andcombines it with ag codes on curves. as the simplest application of our generaltechniques we look at codes on ruled surfaces coming from decomposable vectorbundles. already this construction gives codes that are better than the relatedproduct code. further examples show that we can improve these codes byconstructing more sophisticated t-varieties. these results suggest to lookfurther for good codes on t-varieties.

math.ag cs.it math.it

10.1016/j.jsc.2010.03.008

['ilten', 'süß']

https://arxiv.org/abs/0811.2696

geometric properties of satisfying assignments of random $\epsilon$-1-in-k sat

0811.3116

we study the geometric structure of the set of solutions of random$\epsilon$-1-in-k sat problem. for $l\geq 1$, two satisfying assignments $a$and $b$ are $l$-connected if there exists a sequence of satisfying assignmentsconnecting them by changing at most $l$ bits at a time. we first prove that w.h.p. two assignments of a random $\epsilon$-1-in-$k$sat instance are $o(\log n)$-connected, conditional on being satisfyingassignments. also, there exists $\epsilon_{0}\in (0,\frac{1}{k-2})$ such thatw.h.p. no two satisfying assignments at distance at least $\epsilon_{0}\cdot n$form a "hole" in the set of assignments. we believe that this is true for all$\epsilon >0$, and thus satisfying assignments of a random 1-in-$k$ satinstance form a single cluster.

cs.cc cs.dm

nan

['istrate']

https://arxiv.org/abs/0811.3116

packing and covering properties of subspace codes for error control in random linear network coding

0811.4163

codes in the projective space and codes in the grassmannian over a finitefield - referred to as subspace codes and constant-dimension codes (cdcs),respectively - have been proposed for error control in random linear networkcoding. for subspace codes and cdcs, a subspace metric was introduced tocorrect both errors and erasures, and an injection metric was proposed tocorrect adversarial errors. in this paper, we investigate the packing andcovering properties of subspace codes with both metrics. we first determinesome fundamental geometric properties of the projective space with bothmetrics. using these properties, we then derive bounds on the cardinalities ofpacking and covering subspace codes, and determine the asymptotic rates ofoptimal packing and optimal covering subspace codes with both metrics. ourresults not only provide guiding principles for the code design for errorcontrol in random linear network coding, but also illustrate the differencebetween the two metrics from a geometric perspective. in particular, ourresults show that optimal packing cdcs are optimal packing subspace codes up toa scalar for both metrics if and only if their dimension is half of theirlength (up to rounding). in this case, cdcs suffer from only limited rate lossas opposed to subspace codes with the same minimum distance. we also show thatoptimal covering cdcs can be used to construct asymptotically optimal coveringsubspace codes with the injection metric only.

cs.it math.it

nan

['gadouleau', 'yan']

https://arxiv.org/abs/0811.4163

high resolution dynamical mapping of social interactions with active rfid

0811.4170

in this paper we present an experimental framework to gather data onface-to-face social interactions between individuals, with a high spatial andtemporal resolution. we use active radio frequency identification (rfid)devices that assess contacts with one another by exchanging low-power radiopackets. when individuals wear the beacons as a badge, a persistent radiocontact between the rfid devices can be used as a proxy for a socialinteraction between individuals. we present the results of a pilot studyrecently performed during a conference, and a subsequent preliminary dataanalysis, that provides an assessment of our method and highlights itsversatility and applicability in many areas concerned with human dynamics.

cs.cy cs.hc physics.soc-ph

10.1371/journal.pone.0011596

['barrat', 'cattuto', 'colizza', 'pinton', 'broeck', 'vespignani']

https://arxiv.org/abs/0811.4170

entanglement-assisted communication of classical and quantum information

0811.4227

we consider the problem of transmitting classical and quantum informationreliably over an entanglement-assisted quantum channel. our main result is acapacity theorem that gives a three-dimensional achievable rate region. pointsin the region are rate triples, consisting of the classical communication rate,the quantum communication rate, and the entanglement consumption rate of aparticular coding scheme. the crucial protocol in achieving the boundary pointsof the capacity region is a protocol that we name the classically-enhancedfather protocol. the classically-enhanced father protocol is more general thanother protocols in the family tree of quantum shannon theoretic protocols, inthe sense that several previously known quantum protocols are now childprotocols of it. the classically-enhanced father protocol also shows animprovement over a time-sharing strategy for the case of a qubit dephasingchannel--this result justifies the need for simultaneous coding of classicaland quantum information over an entanglement-assisted quantum channel. ourcapacity theorem is of a multi-letter nature (requiring a limit over many usesof the channel), but it reduces to a single-letter characterization for atleast three channels: the completely depolarizing channel, the quantum erasurechannel, and the qubit dephasing channel.

quant-ph cs.it math.it

10.1109/tit.2010.2053903

['hsieh', 'wilde']

https://arxiv.org/abs/0811.4227

hybrid: a definitional two-level approach to reasoning with higher-order abstract syntax

0811.4367

combining higher-order abstract syntax and (co)induction in a logicalframework is well known to be problematic. previous work described theimplementation of a tool called hybrid, within isabelle hol, which aims toaddress many of these difficulties. it allows object logics to be representedusing higher-order abstract syntax, and reasoned about using tactical theoremproving and principles of (co)induction. in this paper we describe how to useit in a multi-level reasoning fashion, similar in spirit to other meta-logicssuch as twelf. by explicitly referencing provability in a middle layer called aspecification logic, we solve the problem of reasoning by (co)induction in thepresence of non-stratifiable hypothetical judgments, which allow very elegantand succinct specifications of object logic inference rules.

cs.lo

nan

['felty', 'momigliano']

https://arxiv.org/abs/0811.4367

mapping images with the coherence length diagrams

0811.4699

statistical pattern recognition methods based on the coherence length diagram(cld) have been proposed for medical image analyses, such as quantitativecharacterisation of human skin textures, and for polarized light microscopy ofliquid crystal textures. further investigations are made on image mapsoriginated from such diagram and some examples related to irregularity ofmicrostructures are shown.

cs.cv

nan

['sparavigna', 'marazzato']

https://arxiv.org/abs/0811.4699

omnidirectional relay in wireless networks

0812.0038

for wireless networks with multiple sources, an omnidirectional relay schemeis developed, where each node can simultaneously relay different messages indifferent directions. this is accomplished by the decode-and-forward relaystrategy, with each relay binning the multiple messages to be transmitted, inthe same spirit of network coding. specially for the all-source all-castproblem, where each node is an independent source to be transmitted to all theother nodes, this scheme completely eliminates interference in the wholenetwork, and the signal transmitted by any node can be used by any other node.for networks with some kind of symmetry, assuming no beamforming is to beperformed, this omnidirectional relay scheme is capable of achieving themaximum achievable rate.

cs.it math.it

nan

['xie']

https://arxiv.org/abs/0812.0038

dilation, smoothed distance, and minimization diagrams of convex functions

0812.0607

we study voronoi diagrams for distance functions that add together two convexfunctions, each taking as its argument the difference between cartesiancoordinates of two planar points. when the functions do not grow too quickly,then the voronoi diagram has linear complexity and can be constructed innear-linear randomized expected time. additionally, the level sets of thedistances from the sites form a family of pseudocircles in the plane, all cellsin the voronoi diagram are connected, and the set of bisectors separating anyone cell in the diagram from each of the others forms an arrangement ofpseudolines in the plane. we apply these results to the smoothed distance orbiotope transform metric, a geometric analogue of the jaccard distance whosevoronoi diagrams can be used to determine the dilation of a star network with agiven hub. for sufficiently closely spaced points in the plane, the voronoidiagram of smoothed distance has linear complexity and can be computedefficiently. we also experiment with a variant of lloyd's algorithm, adapted tosmoothed distance, to find uniformly spaced point samples with exponentiallydecreasing density around a given point.

cs.cg

nan

['dickerson', 'eppstein', 'wortman']

https://arxiv.org/abs/0812.0607

hierarchy and equivalence of multi-letter quantum finite automata

0812.0852

multi-letter {\it quantum finite automata} (qfas) were a new one-way qfamodel proposed recently by belovs, rosmanis, and smotrovs (lncs, vol. 4588,springer, berlin, 2007, pp. 60-71), and they showed that multi-letter qfas canaccept with no error some regular languages ($(a+b)^{*}b$) that areunacceptable by the one-way qfas. in this paper, we continue to studymulti-letter qfas. we mainly focus on two issues: (1) we show that$(k+1)$-letter qfas are computationally more powerful than $k$-letter qfas,that is, $(k+1)$-letter qfas can accept some regular languages that areunacceptable by any $k$-letter qfa. a comparison with the one-way qfas is madeby some examples; (2) we prove that a $k_{1}$-letter qfa ${\cal a}_1$ andanother $k_{2}$-letter qfa ${\cal a}_2$ are equivalent if and only if they are$(n_{1}+n_{2})^{4}+k-1$-equivalent, and the time complexity of determining theequivalence of two multi-letter qfas using this method is$o(n^{12}+k^{2}n^{4}+kn^{8})$, where $n_{1}$ and $n_{2}$ are the numbers ofstates of ${\cal a}_{1}$ and ${\cal a}_{2}$, respectively, and$k=\max(k_{1},k_{2})$. some other issues are addressed for furtherconsideration.

cs.cc

nan

['qiu', 'yu']

https://arxiv.org/abs/0812.0852

linear-time algorithms for geometric graphs with sublinearly many edge crossings

0812.0893

we provide linear-time algorithms for geometric graphs with sublinearly manycrossings. that is, we provide algorithms running in o(n) time on connectedgeometric graphs having n vertices and k crossings, where k is smaller than nby an iterated logarithmic factor. specific problems we study include voronoidiagrams and single-source shortest paths. our algorithms all run in lineartime in the standard comparison-based computational model; hence, we make noassumptions about the distribution or bit complexities of edge weights, nor dowe utilize unusual bit-level operations on memory words. instead, ouralgorithms are based on a planarization method that "zeroes in" on edgecrossings, together with methods for extending planar separator decompositionsto geometric graphs with sublinearly many crossings. incidentally, ourplanarization algorithm also solves an open computational geometry problem ofchazelle for triangulating a self-intersecting polygonal chain having nsegments and k crossings in linear time, for the case when k is sublinear in nby an iterated logarithmic factor.

cs.cg cs.dm cs.ds cs.gr

10.1137/090759112

['eppstein', 'goodrich', 'strash']

https://arxiv.org/abs/0812.0893

ecotrade - a multi player network game of a tradable permit market for biodiversity credits

0812.0956

ecotrade is a multi player network game of a virtual biodiversity creditmarket. each player controls the land use of a certain amount of parcels on avirtual landscape. the biodiversity credits of a particular parcel depend onneighboring parcels, which may be owned by other players. the game can be usedto study the strategies of players in experiments or classroom games and alsoas a communication tool for stakeholders participating in credit markets thatinclude spatially interdependent credits.

cs.gt

10.1016/j.envsoft.2009.01.003

['hartig', 'horn', 'drechsler']

https://arxiv.org/abs/0812.0956

adaptive uncertainty resolution in bayesian combinatorial optimization problems

0812.1012

in several applications such as databases, planning, and sensor networks,parameters such as selectivity, load, or sensed values are known only with someassociated uncertainty. the performance of such a system (as captured by someobjective function over the parameters) is significantly improved if some ofthese parameters can be probed or observed. in a resource constrainedsituation, deciding which parameters to observe in order to optimize systemperformance itself becomes an interesting and important optimization problem.this general problem is the focus of this paper. one of the most important considerations in this framework is whetheradaptivity is required for the observations. adaptive observations introduceblocking or sequential operations in the system whereas non-adaptiveobservations can be performed in parallel. one of the important questions inthis regard is to characterize the benefit of adaptivity for probes andobservation. we present general techniques for designing constant factor approximations tothe optimal observation schemes for several widely used scheduling and metricobjective functions. we show a unifying technique that relates thisoptimization problem to the outlier version of the corresponding deterministicoptimization. by making this connection, our technique shows constant factorupper bounds for the benefit of adaptivity of the observation schemes. we showthat while probing yields significant improvement in the objective function,being adaptive about the probing is not beneficial beyond constant factors.

cs.ds

nan

['guha', 'munagala']

https://arxiv.org/abs/0812.1012

decidability of the equivalence of multi-letter quantum finite automata

0812.1061

multi-letter {\it quantum finite automata} (qfas) were a quantum variant ofclassical {\it one-way multi-head finite automata} (j. hromkovi\v{c}, actainformatica 19 (1983) 377-384), and it has been shown that this new one-wayqfas (multi-letter qfas) can accept with no error some regular languages$(a+b)^{*}b$ that are unacceptable by the previous one-way qfas. in this paper,we study the decidability of the equivalence of multi-letter qfas, and the maintechnical contributions are as follows: (1) we show that any two automata, a$k_{1}$-letter qfa ${\cal a}_1$ and a $k_{2}$-letter qfa ${\cal a}_2$, over thesame input alphabet $\sigma$ are equivalent if and only if they are$(n^2m^{k-1}-m^{k-1}+k)$-equivalent, where $m=|\sigma|$ is the cardinality of$\sigma$, $k=\max(k_{1},k_{2})$, and $n=n_{1}+n_{2}$, with $n_{1}$ and $n_{2}$being the numbers of states of ${\cal a}_{1}$ and ${\cal a}_{2}$, respectively.when $k=1$, we obtain the decidability of equivalence of measure-once qfas inthe literature. it is worth mentioning that our technical method is essentiallydifferent from that for the decidability of the case of single input alphabet(i.e., $m=1$). (2) however, if we determine the equivalence of multi-letterqfas by checking all strings of length not more than $ n^2m^{k-1}-m^{k-1}+k$,then the worst time complexity is exponential, i.e.,$o(n^6m^{n^2m^{k-1}-m^{k-1}+2k-1})$. therefore, we design a polynomial-time$o(m^{2k-1}n^{8}+km^kn^{6})$ algorithm for determining the equivalence of anytwo multi-letter qfas. here, the time complexity is concerning the number ofstates in the multi-letter qfas, and $k$ is thought of as a constant.

cs.fl cs.cc

nan

['qiu', 'zou', 'li', 'mateus']

https://arxiv.org/abs/0812.1061

cooperative hybrid arq protocols: unified frameworks for protocol analysis

0812.2301

cooperative hybrid-arq (harq) protocols, which can exploit the spatial andtemporal diversities, have been widely studied. the efficiency of cooperativeharq protocols is higher than that of cooperative protocols, becauseretransmissions are only performed when necessary. we classify cooperative harqprotocols as three decode-and-forward based harq (df-harq) protocols and twoamplified-and-forward based (af-harq) protocols. to compare these protocols andobtain the optimum parameters, two unified frameworks are developed forprotocol analysis. using the frameworks, we can evaluate and compare themaximum throughput and outage probabilities according to the snr, the relaylocation, and the delay constraint for the protocols.

cs.it math.it

nan

['byun', 'kim']

https://arxiv.org/abs/0812.2301

on the decoder error probability of rank metric codes and constant-dimension codes

0812.2379

rank metric codes and constant-dimension codes (cdcs) have been consideredfor error control in random network coding. since decoder errors are moredetrimental to system performance than decoder failures, in this paper weinvestigate the decoder error probability (dep) of bounded distance decoders(bdds) for rank metric codes and cdcs. for rank metric codes, we consider achannel motivated by network coding, where errors with the same row space areequiprobable. over such channels, we establish upper bounds on the deps ofbdds, determine the exact dep of bdds for maximum rank distance (mrd) codes,and show that mrd codes have the greatest deps up to a scalar. to evaluate thedeps of bdds for cdcs, we first establish some fundamental geometric propertiesof the projective space. using these geometric properties, we then considerbdds in both subspace and injection metrics and derive analytical expressionsof their deps for cdcs, over a symmetric operator channel, as functions oftheir distance distributions. finally, we focus on cdcs obtained by liftingrank metric codes and establish two important results: first, we deriveasymptotically tight upper bounds on the deps of bdds in both metrics; second,we show that the deps for kk codes are the greatest up to a scalar among allcdcs obtained by lifting rank metric codes.

cs.it math.it

nan

['gadouleau', 'yan']

https://arxiv.org/abs/0812.2379

the violation heap: a relaxed fibonacci-like heap

0812.2851

we give a priority queue that achieves the same amortized bounds as fibonacciheaps. namely, find-min requires o(1) worst-case time, insert, meld anddecrease-key require o(1) amortized time, and delete-min requires $o(\log n)$amortized time. our structure is simple and promises an efficient practicalbehavior when compared to other known fibonacci-like heaps. the main ideabehind our construction is to propagate rank updates instead of performingcascaded cuts following a decrease-key operation, allowing for a relaxedstructure.

cs.ds

nan

['elmasry']

https://arxiv.org/abs/0812.2851

linearly parameterized bandits

0812.3465

we consider bandit problems involving a large (possibly infinite) collectionof arms, in which the expected reward of each arm is a linear function of an$r$-dimensional random vector $\mathbf{z} \in \mathbb{r}^r$, where $r \geq 2$.the objective is to minimize the cumulative regret and bayes risk. when the setof arms corresponds to the unit sphere, we prove that the regret and bayes riskis of order $\theta(r \sqrt{t})$, by establishing a lower bound for anarbitrary policy, and showing that a matching upper bound is obtained through apolicy that alternates between exploration and exploitation phases. thephase-based policy is also shown to be effective if the set of arms satisfies astrong convexity condition. for the case of a general set of arms, we describea near-optimal policy whose regret and bayes risk admit upper bounds of theform $o(r \sqrt{t} \log^{3/2} t)$.

cs.lg

nan

['rusmevichientong', 'tsitsiklis']

https://arxiv.org/abs/0812.3465

indoor channel measurements and communications system design at 60 ghz

0812.4710

this paper presents a brief overview of several studies concerning the indoorwireless communications at 60 ghz performed by the ietr. the characterizationand the modeling of the radio propagation channel are based on severalmeasurement campaigns realized with the channel sounder developed at ietr. sometypical residential environments were also simulated by ray tracing andgaussian beam tracking. the obtained results show a good agreement with thesimilar experimental results. currently, the ietr is developing a high datarate wireless communication system operating at 60 ghz. the single-carrierarchitecture of this system is also presented.

cs.ni

nan

['rakotondrainibe', 'zaharia', 'zein', 'lostanlen']

https://arxiv.org/abs/0812.4710

a pseudopolynomial algorithm for alexandrov's theorem

0812.5030

alexandrov's theorem states that every metric with the global topology andlocal geometry required of a convex polyhedron is in fact the intrinsic metricof a unique convex polyhedron. recent work by bobenko and izmestiev describes adifferential equation whose solution leads to the polyhedron corresponding to agiven metric. we describe an algorithm based on this differential equation tocompute the polyhedron to arbitrary precision given the metric, and prove apseudopolynomial bound on its running time. along the way, we developpseudopolynomial algorithms for computing shortest paths and weighted delaunaytriangulations on a polyhedral surface, even when the surface edges are notshortest paths.

cs.cg

nan

['kane', 'price', 'demaine']

https://arxiv.org/abs/0812.5030

a novel clustering algorithm based upon games on evolving network

0812.5064

this paper introduces a model based upon games on an evolving network, anddevelops three clustering algorithms according to it. in the clusteringalgorithms, data points for clustering are regarded as players who can makedecisions in games. on the network describing relationships among data points,an edge-removing-and-rewiring (err) function is employed to explore in aneighborhood of a data point, which removes edges connecting to neighbors withsmall payoffs, and creates new edges to neighbors with larger payoffs. as such,the connections among data points vary over time. during the evolution ofnetwork, some strategies are spread in the network. as a consequence, clustersare formed automatically, in which data points with the same evolutionarilystable strategy are collected as a cluster, so the number of evolutionarilystable strategies indicates the number of clusters. moreover, the experimentalresults have demonstrated that data points in datasets are clustered reasonablyand efficiently, and the comparison with other algorithms also provides anindication of the effectiveness of the proposed algorithms.

cs.lg cs.cv cs.gt nlin.ao

10.1016/j.eswa.2010.02.050

['li', 'chen', 'he', 'jiang']

https://arxiv.org/abs/0812.5064

maximum entropy on compact groups

0901.0015

on a compact group the haar probability measure plays the role of uniformdistribution. the entropy and rate distortion theory for this uniformdistribution is studied. new results and simplified proofs on convergence ofconvolutions on compact groups are presented and they can be formulated asentropy increases to its maximum. information theoretic techniques and markovchains play a crucial role. the convergence results are also formulated viarate distortion functions. the rate of convergence is shown to be exponential.

cs.it math.it math.pr

10.3390/e11020222

['harremoes']

https://arxiv.org/abs/0901.0015

information inequalities for joint distributions, with interpretations and applications

0901.0044

upper and lower bounds are obtained for the joint entropy of a collection ofrandom variables in terms of an arbitrary collection of subset joint entropies.these inequalities generalize shannon's chain rule for entropy as well asinequalities of han, fujishige and shearer. a duality between the upper andlower bounds for joint entropy is developed. all of these results are shown tobe special cases of general, new results for submodular functions-- thus, theinequalities presented constitute a richly structured class of shannon-typeinequalities. the new inequalities are applied to obtain new results incombinatorics, such as bounds on the number of independent sets in an arbitrarygraph and the number of zero-error source-channel codes, as well as newdeterminantal inequalities in matrix theory. a new inequality for relativeentropies is also developed, along with interpretations in terms of hypothesistesting. finally, revealing connections of the results to literature ineconomics, computer science, and physics are explored.

cs.it math.co math.it math.pr

nan

['madiman', 'tetali']

https://arxiv.org/abs/0901.0044

towards the characterization of individual users through web analytics

0901.0498

we perform an analysis of the way individual users navigate in the web. wefocus primarily in the temporal patterns of they return to a given page. thereturn probability as a function of time as well as the distribution of timeintervals between consecutive visits are measured and found to be independentof the level of activity of single users. the results indicate a rich varietyof individual behaviors and seem to preclude the possibility of defining acharacteristic frequency for each user in his/her visits to a single site.

cs.hc cs.cy physics.soc-ph

10.1007/978-3-642-02469-6_102

['goncalves', 'ramasco']

https://arxiv.org/abs/0901.0498

on the optimal convergence probability of univariate estimation of distribution algorithms

0901.0597

in this paper, we obtain bounds on the probability of convergence to theoptimal solution for the compact genetic algorithm (cga) and the populationbased incremental learning (pbil). we also give a sufficient condition forconvergence of these algorithms to the optimal solution and compute a range ofpossible values of the parameters of these algorithms for which they convergeto the optimal solution with a confidence level.

cs.ne cs.ai

nan

['rastegar']

https://arxiv.org/abs/0901.0597

multicasting correlated multi-source to multi-sink over a network

0901.0608

the problem of network coding with multicast of a single source to multisinkhas first been studied by ahlswede, cai, li and yeung in 2000, in which theyhave established the celebrated max-flow mini-cut theorem on non-physicalinformation flow over a network of independent channels. on the other hand, in1980, han has studied the case with correlated multisource and a single sinkfrom the viewpoint of polymatroidal functions in which a necessary andsufficient condition has been demonstrated for reliable transmission over thenetwork. this paper presents an attempt to unify both cases, which leads toestablish a necessary and sufficient condition for reliable transmission over anetwork multicasting correlated multisource to multisink. here, the problem ofseparation of source coding and channel coding is also discussed.

cs.it math.it

nan

['han']

https://arxiv.org/abs/0901.0608

simple channel coding bounds

0901.0834

new channel coding converse and achievability bounds are derived for a singleuse of an arbitrary channel. both bounds are expressed using a quantity calledthe "smooth 0-divergence", which is a generalization of renyi's divergence oforder 0. the bounds are also studied in the limit of large block-lengths. inparticular, they combine to give a general capacity formula which is equivalentto the one derived by verdu and han.

cs.it math.it

nan

['wang', 'colbeck', 'renner']

https://arxiv.org/abs/0901.0834

weighted well-covered graphs without cycles of length 4, 5, 6 and 7

0901.0858

a graph is well-covered if every maximal independent set has the samecardinality. the recognition problem of well-covered graphs is known to beco-np-complete. let w be a weight function defined on the vertices of g. then gis w-well-covered if all maximal independent sets of g are of the same weight.the set of weight functions w for which a graph is w-well-covered is a vectorspace. we prove that finding the vector space of weight functions under whichan input graph is w-well-covered can be done in polynomial time, if the inputgraph does not contain cycles of length 4, 5, 6 and 7.

cs.dm cs.cc

nan

['levit', 'tankus']

https://arxiv.org/abs/0901.0858

when do nonlinear filters achieve maximal accuracy?

0901.1084

the nonlinear filter for an ergodic signal observed in white noise is said toachieve maximal accuracy if the stationary filtering error vanishes as thesignal to noise ratio diverges. we give a general characterization of themaximal accuracy property in terms of various systems theoretic notions. whenthe signal state space is a finite set explicit necessary and sufficientconditions are obtained, while the linear gaussian case reduces to a classicresult of kwakernaak and sivan (1972).

math.pr cs.it math.it

nan

['van handel']

https://arxiv.org/abs/0901.1084

novel architectures and algorithms for delay reduction in back-pressure scheduling and routing

0901.1312

the back-pressure algorithm is a well-known throughput-optimal algorithm.however, its delay performance may be quite poor even when the traffic load isnot close to network capacity due to the following two reasons. first, eachnode has to maintain a separate queue for each commodity in the network, andonly one queue is served at a time. second, the back-pressure routing algorithmmay route some packets along very long routes. in this paper, we presentsolutions to address both of the above issues, and hence, improve the delayperformance of the back-pressure algorithm. one of the suggested solutions alsodecreases the complexity of the queueing data structures to be maintained ateach node.

cs.ni

nan

['bui', 'srikant', 'stolyar']

https://arxiv.org/abs/0901.1312

multishot codes for network coding: bounds and a multilevel construction

0901.1655

the subspace channel was introduced by koetter and kschischang as an adequatemodel for the communication channel from the source node to a sink node of amulticast network that performs random linear network coding. so far, attentionhas been given to one-shot subspace codes, that is, codes that use the subspacechannel only once. in contrast, this paper explores the idea of using thesubspace channel more than once and investigates the so called multishotsubspace codes. we present definitions for the problem, a motivating example,lower and upper bounds for the size of codes, and a multilevel construction ofcodes based on block-coded modulation.

cs.it math.it

10.1109/isit.2009.5205750

['nobrega', 'uchoa-filho']

https://arxiv.org/abs/0901.1655

pilot contamination and precoding in multi-cell tdd systems

0901.1703

this paper considers a multi-cell multiple antenna system with precoding usedat the base stations for downlink transmission. for precoding at the basestations, channel state information (csi) is essential at the base stations. apopular technique for obtaining this csi in time division duplex (tdd) systemsis uplink training by utilizing the reciprocity of the wireless medium. thispaper mathematically characterizes the impact that uplink training has on theperformance of such multi-cell multiple antenna systems. when non-orthogonaltraining sequences are used for uplink training, the paper shows that theprecoding matrix used by the base station in one cell becomes corrupted by thechannel between that base station and the users in other cells in anundesirable manner. this paper analyzes this fundamental problem of pilotcontamination in multi-cell systems. furthermore, it develops a new multi-cellmmse-based precoding method that mitigate this problem. in addition to being alinear precoding method, this precoding method has a simple closed-formexpression that results from an intuitive optimization problem formulation.numerical results show significant performance gains compared to certainpopular single-cell precoding methods.

cs.it math.it

nan

['jose', 'ashikhmin', 'marzetta', 'vishwanath']

https://arxiv.org/abs/0901.1703

interference avoidance game in the gaussian interference channel: sub-optimal and optimal schemes

0901.1924

this paper considers a distributed interference avoidance problem employingfrequency assignment in the gaussian interference channel (ic). we divide thecommon channel into several subchannels and each user chooses the subchannelwith less amount of interference from other users as the transmit channel. thismechanism named interference avoidance in this paper can be modeled as acompetitive game model. and a completely autonomous distributed iterativealgorithm called tdistributed interference avoidance algorithm (dia) is adoptedto achieve the nash equilibriumt (ne) of the game. due to the self-optimum, diais a sub-optimal algorithm. therefore, through introducing an optimalcompensation into the competitive game model, we successfully develop acompensation-based game model to approximate the optimal interference avoidanceproblem. moreover, an optimal algorithm called iterative optimal interferenceavoidance algorithm (ioia) is proposed to reach the optimality of theinterference avoidance scheme. we analyze the implementation complexities ofthe two algorithms. we also give the proof on the convergence of the proposedalgorithms. the performance upper bound and lower bound are also derived forthe proposed algorithms. the simulation results show that ioia does reach theoptimality under condition of interference avoidance mechanism.

cs.it math.it

nan

['jing', 'bai', 'ma', 'li']

https://arxiv.org/abs/0901.1924

concept-oriented model and query language

0901.2224

we describe a new approach to data modeling, called the concept-orientedmodel (com), and a novel concept-oriented query language (coql). the model isbased on three principles: duality principle postulates that any element is acouple consisting of one identity and one entity, inclusion principlepostulates that any element has a super-element, and order principle assumesthat any element has a number of greater elements within a partially orderedset. concept-oriented query language is based on a new data modeling construct,called concept, inclusion relation between concepts, and concept partialordering in which greater concepts are represented by their field types. it isdemonstrated how com and coql can be used to solve three general data modelingtasks: logical navigation, multidimensional analysis and inference. logicalnavigation is based on two operations of projection and de-projection.multidimensional analysis uses product operation for producing a cube fromlevel concepts chosen along the chosen dimension paths. inference is defined asa two-step procedure where input constraints are first propagated downwardsusing de-projection and then the constrained result is propagated upwards usingprojection.

cs.db

nan

['savinov']

https://arxiv.org/abs/0901.2224

distributed large scale network utility maximization

0901.2684

recent work by zymnis et al. proposes an efficient primal-dual interior-pointmethod, using a truncated newton method, for solving the network utilitymaximization (num) problem. this method has shown superior performance relativeto the traditional dual-decomposition approach. other recent work by bickson etal. shows how to compute efficiently and distributively the newton step, whichis the main computational bottleneck of the newton method, utilizing thegaussian belief propagation algorithm. in the current work, we combine both approaches to create an efficientdistributed algorithm for solving the num problem. unlike the work of zymnis,which uses a centralized approach, our new algorithm is easily distributed.using an empirical evaluation we show that our new method outperforms previousapproaches, including the truncated newton method and dual-decompositionmethods. as an additional contribution, this is the first work that evaluatesthe performance of the gaussian belief propagation algorithm vs. thepreconditioned conjugate gradient method, for a large scale problem.

cs.it cs.dc math.it math.oc

10.1109/isit.2009.5205655

['bickson', 'tock', 'zymnis', 'boyd', 'dolev']

https://arxiv.org/abs/0901.2684

a hybrid multicast-unicast infrastructure for efficient publish-subscribe in enterprise networks

0901.2687

one of the main challenges in building a large scale publish-subscribeinfrastructure in an enterprise network, is to provide the subscribers with therequired information, while minimizing the consumed host and network resources.typically, previous approaches utilize either ip multicast or point-to-pointunicast for efficient dissemination of the information. in this work, we propose a novel hybrid framework, which is a combination ofboth multicast and unicast data dissemination. our hybrid framework allows usto take the advantages of both multicast and unicast, while avoiding theirdrawbacks. we investigate several algorithms for computing the best mapping ofpublishers' transmissions into multicast and unicast transport. using extensive simulations, we show that our hybrid framework reducesconsumed host and network resources, outperforming traditional solutions. toinsure the subscribers interests closely resemble those of real-world settings,our simulations are based on stock market data and on recorded ibm webshperesubscriptions.

cs.ni cs.dc

10.1145/1815695.1815722

['bickson', 'hoch', 'naaman', 'tock']

https://arxiv.org/abs/0901.2687

peer-to-peer secure multi-party numerical computation facing malicious adversaries

0901.2689

we propose an efficient framework for enabling secure multi-party numericalcomputations in a peer-to-peer network. this problem arises in a range ofapplications such as collaborative filtering, distributed computation of trustand reputation, monitoring and other tasks, where the computing nodes isexpected to preserve the privacy of their inputs while performing a jointcomputation of a certain function. although there is a rich literature in thefield of distributed systems security concerning secure multi-partycomputation, in practice it is hard to deploy those methods in very large scalepeer-to-peer networks. in this work, we try to bridge the gap betweentheoretical algorithms in the security domain, and a practical peer-to-peerdeployment. we consider two security models. the first is the semi-honest model wherepeers correctly follow the protocol, but try to reveal private information. weprovide three possible schemes for secure multi-party numerical computation forthis model and identify a single light-weight scheme which outperforms theothers. using extensive simulation results over real internet topologies, wedemonstrate that our scheme is scalable to very large networks, with up tomillions of nodes. the second model we consider is the malicious peers model,where peers can behave arbitrarily, deliberately trying to affect the resultsof the computation as well as compromising the privacy of other peers. for thismodel we provide a fourth scheme to defend the execution of the computationagainst the malicious peers. the proposed scheme has a higher complexityrelative to the semi-honest model. overall, we provide the peer-to-peer networkdesigner a set of tools to choose from, based on the desired level of security.

cs.cr cs.ni

10.1007/s12083-009-0051-9

['bickson', 'reinman', 'dolev', 'pinkas']

https://arxiv.org/abs/0901.2689

language recognition by generalized quantum finite automata with unbounded error (abstract & poster)

0901.2703

in this note, we generalize the results of arxiv:0901.2703v1 we show that allone-way quantum finite automaton (qfa) models that are at least as general askondacs-watrous qfa's are equivalent in power to classical probabilistic finiteautomata in this setting. unlike their probabilistic counterparts, allowing thetape head to stay put for some steps during its traversal of the input doesenlarge the class of languages recognized by such qfa's with unbounded error.(note that, the proof of theorem 1 in the abstract was presented in theprevious version (arxiv:0901.2703v1).)

cs.cc

nan

['yakaryilmaz', 'say']

https://arxiv.org/abs/0901.2703

an extension of the order bound for ag codes

0901.2864

the most successful method to obtain lower bounds for the minimum distance ofan algebraic geometric code is the order bound, which generalizes the feng-raobound. we provide a significant extension of the bound that improves the orderbounds by beelen and by duursma and park. we include an exhaustive numericalcomparison of the different bounds for 10168 two-point codes on the suzukicurve of genus g=124 over the field of 32 elements. keywords: algebraicgeometric code, order bound, suzuki curve.

math.nt cs.it math.ag math.it

10.1007/978-3-642-02181-7

['duursma', 'kirov']

https://arxiv.org/abs/0901.2864

entropy measures vs. algorithmic information

0901.2903

algorithmic entropy and shannon entropy are two conceptually differentinformation measures, as the former is based on size of programs and the laterin probability distributions. however, it is known that, for any recursiveprobability distribution, the expected value of algorithmic entropy equals itsshannon entropy, up to a constant that depends only on the distribution. westudy if a similar relationship holds for r\'{e}nyi and tsallis entropies oforder $\alpha$, showing that it only holds for r\'{e}nyi and tsallis entropiesof order 1 (i.e., for shannon entropy). regarding a time bounded analoguerelationship, we show that, for distributions such that the cumulativeprobability distribution is computable in time $t(n)$, the expected value oftime-bounded algorithmic entropy (where the alloted time is $nt(n)\log(nt(n))$) is in the same range as the unbounded version. so, for thesedistributions, shannon entropy captures the notion of computationallyaccessible information. we prove that, for universal time-bounded distribution$\m^t(x)$, tsallis and r\'{e}nyi entropies converge if and only if $\alpha$ isgreater than 1.

cs.it cs.cc math.it

nan

['teixeira', 'souto', 'matos', 'antunes']

https://arxiv.org/abs/0901.2903

on linear balancing sets

0901.3170

let n be an even positive integer and f be the field \gf(2). a word in f^n iscalled balanced if its hamming weight is n/2. a subset c \subseteq f^n$ iscalled a balancing set if for every word y \in f^n there is a word x \in c suchthat y + x is balanced. it is shown that most linear subspaces of f^n ofdimension slightly larger than 3/2\log_2(n) are balancing sets. ageneralization of this result to linear subspaces that are "almost balancing"is also presented. on the other hand, it is shown that the problem of decidingwhether a given set of vectors in f^n spans a balancing set, is np-hard. anapplication of linear balancing sets is presented for designing efficienterror-correcting coding schemes in which the codewords are balanced.

cs.it cs.dm math.it

10.3934/amc.2010.4.345

['mazumdar', 'roth', 'vontobel']

https://arxiv.org/abs/0901.3170

a low density lattice decoder via non-parametric belief propagation

0901.3197

the recent work of sommer, feder and shalvi presented a new family of codescalled low density lattice codes (ldlc) that can be decoded efficiently andapproach the capacity of the awgn channel. a linear time iterative decodingscheme which is based on a message-passing formulation on a factor graph isgiven. in the current work we report our theoretical findings regarding the relationbetween the ldlc decoder and belief propagation. we show that the ldlc decoderis an instance of non-parametric belief propagation and further connect it tothe gaussian belief propagation algorithm. our new results enable borrowingknowledge from the non-parametric and gaussian belief propagation domains intothe ldlc domain. specifically, we give more general convergence conditions forconvergence of the ldlc decoder (under the same assumptions of the originalldlc convergence analysis). we discuss how to extend the ldlc decoder fromlatin square to full rank, non-square matrices. we propose an efficientconstruction of sparse generator matrix and its matching decoder. we reportpreliminary experimental results which show our decoder has comparable symbolto error rate compared to the original ldlc decoder.%

cs.it math.it

10.1109/allerton.2009.5394798

['bickson', 'ihler', 'dolev']

https://arxiv.org/abs/0901.3197

computing rooted and unrooted maximum consistent supertrees

0901.3299

a chief problem in phylogenetics and database theory is the computation of amaximum consistent tree from a set of rooted or unrooted trees. a standardinput are triplets, rooted binary trees on three leaves, or quartets, unrootedbinary trees on four leaves. we give exact algorithms constructing rooted andunrooted maximum consistent supertrees in time o(2^n n^5 m^2 log(m)) for a setof m triplets (quartets), each one distinctly leaf-labeled by some subset of nlabels. the algorithms extend to weighted triplets (quartets). we furtherpresent fast exact algorithms for constructing rooted and unrooted maximumconsistent trees in polynomial space. finally, for a set t of m rooted orunrooted trees with maximum degree d and distinctly leaf-labeled by some subsetof a set l of n labels, we compute, in o(2^{md} n^m m^5 n^6 log(m)) time, atree distinctly leaf-labeled by a maximum-size subset x of l that all trees int, when restricted to x, are consistent with.

cs.dm cs.ds

nan

['van iersel', 'mnich']

https://arxiv.org/abs/0901.3299

a boundary approximation algorithm for distributed sensor networks

0901.3384

we present an algorithm for boundary approximation in locally-linked sensornetworks that communicate with a remote monitoring station. delaunaytriangulations and voronoi diagrams are used to generate a sensor communicationnetwork and define boundary segments between sensors, respectively. theproposed algorithm reduces remote station communication by approximatingboundaries via a decentralized computation executed within the sensor network.moreover, the algorithm identifies boundaries based on differences betweenneighboring sensor readings, and not absolute sensor values. an analysis of thebandwidth consumption of the algorithm is presented and compared to two naiveapproaches. the proposed algorithm reduces the amount of remote communication(compared to the naive approaches) and becomes increasingly useful in networkswith more nodes.

cs.dc

nan

['ham', 'rodriguez']

https://arxiv.org/abs/0901.3384

symmetric tensor decomposition

0901.3706

we present an algorithm for decomposing a symmetric tensor, of dimension nand order d as a sum of rank-1 symmetric tensors, extending the algorithm ofsylvester devised in 1886 for binary forms. we recall the correspondencebetween the decomposition of a homogeneous polynomial in n variables of totaldegree d as a sum of powers of linear forms (waring's problem), incidenceproperties on secant varieties of the veronese variety and the representationof linear forms as a linear combination of evaluations at distinct points. thenwe reformulate sylvester's approach from the dual point of view. exploitingthis duality, we propose necessary and sufficient conditions for the existenceof such a decomposition of a given rank, using the properties of hankel (andquasi-hankel) matrices, derived from multivariate polynomials and normal formcomputations. this leads to the resolution of polynomial equations of smalldegree in non-generic cases. we propose a new algorithm for symmetric tensordecomposition, based on this characterization and on linear algebracomputations with these hankel matrices. the impact of this contribution istwo-fold. first it permits an efficient computation of the decomposition of anytensor of sub-generic rank, as opposed to widely used iterative algorithms withunproved global convergence (e.g. alternate least squares or gradientdescents). second, it gives tools for understanding uniqueness conditions, andfor detecting the rank.

cs.sc math.ag

nan

['brachat', 'comon', 'mourrain', 'tsigaridas']

https://arxiv.org/abs/0901.3706

remembering what we like: toward an agent-based model of web traffic

0901.3839

analysis of aggregate web traffic has shown that pagerank is a poor model ofhow people actually navigate the web. using the empirical traffic patternsgenerated by a thousand users over the course of two months, we characterizethe properties of web traffic that cannot be reproduced by markovian models, inwhich destinations are independent of past decisions. in particular, we showthat the diversity of sites visited by individual users is smaller and morebroadly distributed than predicted by the pagerank model; that link traffic ismore broadly distributed than predicted; and that the time between consecutivevisits to the same site by a user is less broadly distributed than predicted.to account for these discrepancies, we introduce a more realistic navigationmodel in which agents maintain individual lists of bookmarks that are used asteleportation targets. the model can also account for branching, a trafficproperty caused by browser features such as tabs and the back button. the modelreproduces aggregate traffic patterns such as site popularity, while alsogenerating more accurate predictions of diversity, link traffic, and returntime distributions. this model for the first time allows us to capture theextreme heterogeneity of aggregate traffic measurements while explaining themore narrowly focused browsing patterns of individual users.

cs.hc cs.cy cs.ir cs.ma physics.soc-ph

nan

['goncalves', 'meiss', 'ramasco', 'flammini', 'menczer']

https://arxiv.org/abs/0901.3839

distributed lossy averaging

0901.4134

an information theoretic formulation of the distributed averaging problempreviously studied in computer science and control is presented. we assume anetwork with m nodes each observing a wgn source. the nodes communicate andperform local processing with the goal of computing the average of the sourcesto within a prescribed mean squared error distortion. the network ratedistortion function r^*(d) for a 2-node network with correlated gaussiansources is established. a general cutset lower bound on r^*(d) is establishedand shown to be achievable to within a factor of 2 via a centralized protocolover a star network. a lower bound on the network rate distortion function fordistributed weighted-sum protocols, which is larger in order than the cutsetbound by a factor of log m is established. an upper bound on the network ratedistortion function for gossip-base weighted-sum protocols, which is only loglog m larger in order than the lower bound for a complete graph network, isestablished. the results suggest that using distributed protocols results in afactor of log m increase in order relative to centralized protocols.

cs.it math.it

nan

['su', 'gamal']

https://arxiv.org/abs/0901.4134

fixing convergence of gaussian belief propagation

0901.4192

gaussian belief propagation (gabp) is an iterative message-passing algorithmfor inference in gaussian graphical models. it is known that when gabpconverges it converges to the correct map estimate of the gaussian randomvector and simple sufficient conditions for its convergence have beenestablished. in this paper we develop a double-loop algorithm for forcingconvergence of gabp. our method computes the correct map estimate even in caseswhere standard gabp would not have converged. we further extend thisconstruction to compute least-squares solutions of over-constrained linearsystems. we believe that our construction has numerous applications, since thegabp algorithm is linked to solution of linear systems of equations, which is afundamental problem in computer science and engineering. as a case study, wediscuss the linear detection problem. we show that using our new construction,we are able to force convergence of montanari's linear detection algorithm, incases where it would originally fail. as a consequence, we are able to increasesignificantly the number of users that can transmit concurrently.

cs.it cs.lg math.it stat.co

10.1109/isit.2009.5205777

['johnson', 'bickson', 'dolev']

https://arxiv.org/abs/0901.4192

physarum boats: if plasmodium sailed it would never leave a port

0901.4466

plasmodium of \emph{physarum polycephalum} is a single huge (visible by nakedeye) cell with myriad of nuclei. the plasmodium is a promising substrate fornon-classical, nature-inspired, computing devices. it is capable forapproximation of shortest path, computation of planar proximity graphs andplane tessellations, primitive memory and decision-making. the uniqueproperties of the plasmodium make it an ideal candidate for a role of amorphousbiological robots with massive parallel information processing and distributedinputs and outputs. we show that when adhered to light-weight object resting ona water surface the plasmodium can propel the object by oscillating itsprotoplasmic pseudopodia. in experimental laboratory conditions andcomputational experiments we study phenomenology of the plasmodium-floatersystem, and possible mechanisms of controlling motion of objects propelled byon board plasmodium.

cs.ro q-bio.cb

10.1080/11762320902863890

['adamatzky']

https://arxiv.org/abs/0901.4466

space efficient secret sharing: a recursive approach

0901.4814

this paper presents a recursive secret sharing technique that distributes k-1secrets of length b each into n shares such that each share is effectively oflength (n/(k-1))*b and any k pieces suffice for reconstructing all the k-1secrets. since n/(k-1) is near the optimal factor of n/k, and can be chosen tobe close to 1, the proposed technique is space efficient. furthermore, eachshare is information theoretically secure, i.e. it does not depend on anyunproven assumption of computational intractability. such a recursive techniquehas potential applications in secure and reliable storage of information on theweb and in sensor networks.

cs.cr

nan

['parakh', 'kak']

https://arxiv.org/abs/0901.4814

a mathematical basis for the chaining of lossy interface adapters

0901.4835

despite providing similar functionality, multiple network services mayrequire the use of different interfaces to access the functionality, and thisproblem will only get worse with the widespread deployment of ubiquitouscomputing environments. one way around this problem is to use interfaceadapters that adapt one interface into another. chaining these adapters allowsflexible interface adaptation with fewer adapters, but the loss incurred due toimperfect interface adaptation must be considered. this paper outlines amathematical basis for analyzing the chaining of lossy interface adapters. wealso show that the problem of finding an optimal interface adapter chain isnp-complete.

cs.dm cs.dc cs.se

10.1049/iet-sen.2009.0019

['chung', 'lee']

https://arxiv.org/abs/0901.4835

a historical perspective on developing foundations iinfo(tm) information systems: iconsult(tm) and ientertain(tm) apps using idescribers(tm) information integration for iorgs(tm) information systems

0901.4934

technology now at hand can integrate all kinds of digital information forindividuals, groups, and organizations so their information usefully linkstogether. iinfo(tm) information integration works by making connectionsincluding examples like the following: - a statistical connection between "being in a traffic jam" and "driving indowntown trenton between 5pm and 6pm on a weekday." - a terminological connection between "msr" and "microsoft research." - a causal connection between "joining a group" and "being a member of thegroup." - a syntactic connection between "a pin dropped" and "a dropped pin." - a biological connection between "a dolphin" and "a mammal". - a demographic connection between "undocumented residents of california" and"7% of the population of california." - a geographical connection between "leeds" and "england." - a temporal connection between "turning on a computer" and "joining anon-line discussion." by making these connections, iinfo offers tremendous value for individuals,families, groups, and organizations in making more effective use of informationtechnology. in practice, integrated information is invariably pervasively inconsistent.therefore iinfo must be able to make connections even in the face ofinconsistency. the business of iinfo is not to make difficult decisions likedeciding the ultimate truth or probability of propositions. instead it providesmeans for processing information and carefully recording its provenanceincluding arguments (including arguments about arguments) for and againstpropositions that is used by iconsult(tm) and ientertain(tm) apps in iorgs(tm)information systems. a historical perspective on the above questions is highly pertinent to thecurrent quest to develop foundations for privacy-friendly client-cloudcomputing.

cs.dc cs.db cs.lo

nan

['hewitt']

https://arxiv.org/abs/0901.4934

the complexity of nash equilibria in simple stochastic multiplayer games

0902.0101

we analyse the computational complexity of finding nash equilibria in simplestochastic multiplayer games. we show that restricting the search space toequilibria whose payoffs fall into a certain interval may lead toundecidability. in particular, we prove that the following problem isundecidable: given a game g, does there exist a pure-strategy nash equilibriumof g where player 0 wins with probability 1. moreover, this problem remainsundecidable if it is restricted to strategies with (unbounded) finite memory.however, if mixed strategies are allowed, decidability remains an open problem.one way to obtain a provably decidable variant of the problem is restrictingthe strategies to be positional or stationary. for the complexity of these twoproblems, we obtain a common lower bound of np and upper bounds of np andpspace respectively.

cs.gt cs.cc cs.lo

10.1007/978-3-642-02930-1_25

['ummels', 'wojtczak']

https://arxiv.org/abs/0902.0101

an optimal multi-unit combinatorial procurement auction with single minded bidders

0902.0524

the current art in optimal combinatorial auctions is limited to handling thecase of single units of multiple items, with each bidder bidding on exactly onebundle (single minded bidders). this paper extends the current art by proposingan optimal auction for procuring multiple units of multiple items when thebidders are single minded. the auction minimizes the cost of procurement whilesatisfying bayesian incentive compatibility and interim individual rationality.under appropriate regularity conditions, this optimal auction also satisfiesdominant strategy incentive compatibility.

cs.gt

nan

['gujar', 'narahari']

https://arxiv.org/abs/0902.0524

a unified perspective on parity- and syndrome-based binary data compression using off-the-shelf turbo codecs

0902.0562

we consider the problem of compressing memoryless binary data with or withoutside information at the decoder. we review the parity- and the syndrome-basedapproaches and discuss their theoretical limits, assuming that there exists avirtual binary symmetric channel between the source and the side information,and that the source is not necessarily uniformly distributed. we take afactor-graph-based approach in order to devise how to take full advantage ofthe ready-available iterative decoding procedures when turbo codes areemployed, in both a parity- or a syndrome-based fashion. we end up obtaining aunified decoder formulation that holds both for error-free and for error-proneencoder-to-decoder transmission over generic channels. to support thetheoretical results, the different compression systems analyzed in the paperare also experimentally tested. they are compared against several differentapproaches proposed in literature and shown to be competitive in a variety ofcases.

cs.it math.it

nan

['cappellari', 'de giusti']

https://arxiv.org/abs/0902.0562

interference and congestion aware gradient broadcasting routing for wireless sensor networks

0902.0746

this paper addresses the problem of reliable transmission of data through asensor network. we focus on networks rapidly deployed in harsh environments.for these networks, important design requirements are fast data transmissionand rapid network setup, as well as minimized energy consumption for increasednetwork lifetime. we propose a novel broadcasting solution that accounts forthe interference impact and the congestion level of the channel, in order toimprove robustness, energy consumption and delay performance, compared to abenchmark routing protocol, the grab algorithm. three solutions are proposed:p-grab, a probabilistic routing algorithm for interference mitigation, u-grab,a utility-based algorithm that adjusts to real-time congestion and up-grab, acombination of p-grab and u-grab. it is shown that p-grab provides the bestperformance for geometry-aware networks while the u-grab approach is the bestoption for unreliable and unstable networks.

cs.ni

nan

['jaffrès-runser', 'comaniciu', 'gorce']

https://arxiv.org/abs/0902.0746

a multiobjective optimization framework for routing in wireless ad hoc networks

0902.0782

wireless ad hoc networks are seldom characterized by one single performancemetric, yet the current literature lacks a flexible framework to assist incharacterizing the design tradeoffs in such networks. in this work, we addressthis problem by proposing a new modeling framework for routing in ad hocnetworks, which used in conjunction with metaheuristic multiobjective searchalgorithms, will result in a better understanding of network behavior andperformance when multiple criteria are relevant. our approach is to take aholistic view of the network that captures the cross-interactions amonginterference management techniques implemented at various layers of theprotocol stack. the resulting framework is a complex multiobjectiveoptimization problem that can be efficiently solved through existingmultiobjective search techniques. in this contribution, we present the paretooptimal sets for an example sensor network when delay, robustness and energyare considered. the aim of this paper is to present the framework and hence forconciseness purposes, the multiobjective optimization search is not developedherein.

cs.ni cs.pf

nan

['jaffrès-runser', 'comaniciu', 'gorce']

https://arxiv.org/abs/0902.0782

on the gaussian mac with imperfect feedback

0902.0947

new achievable rate regions are derived for the two-user additive whitegaussian multiple-access channel with noisy feedback. the regions exhibit thefollowing two properties. irrespective of the (finite) gaussian feedback-noisevariances, the regions include rate points that lie outside the no-feedbackcapacity region, and when the feedback-noise variances tend to 0 the regionsconverge to the perfect-feedback capacity region. the new achievable regionsalso apply to the partial-feedback setting where one of the transmitters has anoisy feedback link and the other transmitter has no feedback at all. again,irrespective of the (finite) noise variance on the feedback link, the regionsinclude rate points that lie outside the no-feedback capacity region. moreover,in the case of perfect partial feedback, i.e., where the only feedback link isnoise-free, for certain channel parameters the new regions include rate pointsthat lie outside the cover-leung region. this answers in the negative thequestion posed by van der meulen as to whether the cover-leung region equalsthe capacity region of the gaussian multiple-access channel with perfectpartial feedback. finally, we propose new achievable regions also for a settingwhere the receiver is cognizant of the realizations of the noise sequences onthe feedback links.

cs.it math.it

nan

['lapidoth', 'wigger']

https://arxiv.org/abs/0902.0947

compilation of extended recursion in call-by-value functional languages

0902.1257

this paper formalizes and proves correct a compilation scheme formutually-recursive definitions in call-by-value functional languages. thisscheme supports a wider range of recursive definitions than previous methods.we formalize our technique as a translation scheme to a lambda-calculusfeaturing in-place update of memory blocks, and prove the translation to becorrect.

cs.pl

10.1007/s10990-009-9042-z

['hirschowitz', 'leroy', 'wells']

https://arxiv.org/abs/0902.1257

fundamental delay bounds in peer-to-peer chunk-based real-time streaming systems

0902.1394

this paper addresses the following foundational question: what is the maximumtheoretical delay performance achievable by an overlay peer-to-peer streamingsystem where the streamed content is subdivided into chunks? as shown in thispaper, when posed for chunk-based systems, and as a consequence of thestore-and-forward way in which chunks are delivered across the network, thisquestion has a fundamentally different answer with respect to the case ofsystems where the streamed content is distributed through one or more flows(sub-streams). to circumvent the complexity emerging when directly dealing withdelay, we express performance in term of a convenient metric, called "streamdiffusion metric". we show that it is directly related to the end-to-endminimum delay achievable in a p2p streaming network. in a homogeneous scenario,we derive a performance bound for such metric, and we show how this boundrelates to two fundamental parameters: the upload bandwidth available at eachnode, and the number of neighbors a node may deliver chunks to. in this bound,k-step fibonacci sequences do emerge, and appear to set the fundamental lawsthat characterize the optimal operation of chunk-based systems.

cs.pf cs.mm

nan

['bianchi', 'melazzi', 'bracciale', 'piccolo', 'salsano']

https://arxiv.org/abs/0902.1394

on the bures volume of separable quantum states

0902.1505

we obtain two sided estimates for the bures volume of an arbitrary subset ofthe set of $n\times n$ density matrices, in terms of the hilbert-schmidt volumeof that subset. for general subsets, our results are essentially optimal (forlarge $n$). as applications, we derive in particular nontrivial lower and upperbounds for the bures volume of sets of separable states and for sets of stateswith positive partial transpose. pacs numbers: 02.40.ft, 03.65.db, 03.65.ud, 03.67.mn

quant-ph cs.it math.fa math.it math.mg

10.1063/1.3187216

['ye']

https://arxiv.org/abs/0902.1505

feature hashing for large scale multitask learning

0902.2206

empirical evidence suggests that hashing is an effective strategy fordimensionality reduction and practical nonparametric estimation. in this paperwe provide exponential tail bounds for feature hashing and show that theinteraction between random subspaces is negligible with high probability. wedemonstrate the feasibility of this approach with experimental results for anew use case -- multitask learning with hundreds of thousands of tasks.

cs.ai

nan

['weinberger', 'dasgupta', 'attenberg', 'langford', 'smola']

https://arxiv.org/abs/0902.2206

inseparability and strong hypotheses for disjoint np pairs

0902.2674

this paper investigates the existence of inseparable disjoint pairs of nplanguages and related strong hypotheses in computational complexity. our maintheorem says that, if np does not have measure 0 in exp, then there existdisjoint pairs of np languages that are p-inseparable, in facttime(2^(n^k))-inseparable. we also relate these conditions to strong hypothesesconcerning randomness and genericity of disjoint pairs.

cs.cc

nan

['fortnow', 'lutz', 'mayordomo']

https://arxiv.org/abs/0902.2674

a formal calculus on the riordan near algebra

0902.2853

the riordan group is the semi-direct product of a multiplicative group ofinvertible series and a group, under substitution, of non units. the riordannear algebra, as introduced in this paper, is the cartesian product of thealgebra of formal power series and its principal ideal of non units, equippedwith a product that extends the multiplication of the riordan group. the lateris naturally embedded as a subgroup of units into the former. in this paper, weprove the existence of a formal calculus on the riordan algebra. this formalcalculus plays a role similar to those of holomorphic calculi in the banach orfr\'echet algebras setting, but without the constraint of a radius ofconvergence. using this calculus, we define \emph{en passant} a notion ofgeneralized powers in the riordan group.

cs.sc math.co

nan

['poinsot', 'duchamp']

https://arxiv.org/abs/0902.2853

error-correcting tournaments

0902.3176

we present a family of pairwise tournaments reducing $k$-class classificationto binary classification. these reductions are provably robust against aconstant fraction of binary errors. the results improve on the pecocconstruction \cite{secoc} with an exponential improvement in computation, from$o(k)$ to $o(\log_2 k)$, and the removal of a square root in the regretdependence, matching the best possible computation and regret up to a constant.

cs.ai cs.lg

nan

['beygelzimer', 'langford', 'ravikumar']

https://arxiv.org/abs/0902.3176

on optimum end-to-end distortion in mimo systems

0902.3595

this paper presents the joint impact of the numbers of antennas,source-to-channel bandwidth ratio and spatial correlation on the optimumexpected end-to-end distortion in an outage-free mimo system. in particular,based on an analytical expression valid for any snr, a closed-form expressionof the optimum asymptotic expected end-to-end distortion valid for high snr isderived. it is comprised of the optimum distortion exponent and themultiplicative optimum distortion factor. demonstrated by the simulationresults, the analysis on the joint impact of the optimum distortion exponentand the optimum distortion factor explains the behavior of the optimum expectedend-to-end distortion varying with the numbers of antennas, source-to-channelbandwidth ratio and spatial correlation. it is also proved that as thecorrelation tends to zero, the optimum asymptotic expected end-to-enddistortion in the setting of correlated channel approaches that in the settingof uncorrelated channel. the results in this paper could be performanceobjectives for analog-source transmission systems. to some extend, they areinstructive for system design.

cs.it math.it

nan

['chen', 'slock']

https://arxiv.org/abs/0902.3595

a self-contained and easily accessible discussion of the method of descente infinie and fermat's only explicitly known proof by descente infinie

0902.3623

we present the only proof of pierre fermat by descente infinie that is knownto exist today. as the text of its latin original requires active mathematicalinterpretation, it is more a proof sketch than a proper mathematical proof. wediscuss descente infinie from the mathematical, logical, historical,linguistic, and refined logic-historical points of view. we provide therequired preliminaries from number theory and develop a self-contained proof ina modern form, which nevertheless is intended to follow fermat's ideas closely.we then annotate an english translation of fermat's original proof with termsfrom the modern proof. including all important facts, we present a concise andself-contained discussion of fermat's proof sketch, which is easily accessibleto laymen in number theory as well as to laymen in the history of mathematics,and which provides new clarification of the method of descente infinie to theexperts in these fields. last but not least, this paper fills a gap regardingthe easy accessibility of the subject.

cs.ai cs.lo

nan

['wirth']

https://arxiv.org/abs/0902.3623

distributed agreement in tile self-assembly

0902.3631

laboratory investigations have shown that a formal theory of fault-tolerancewill be essential to harness nanoscale self-assembly as a medium ofcomputation. several researchers have voiced an intuition that self-assemblyphenomena are related to the field of distributed computing. this paperformalizes some of that intuition. we construct tile assembly systems that areable to simulate the solution of the wait-free consensus problem in somedistributed systems. (for potential future work, this may allow binding errorsin tile assembly to be analyzed, and managed, with positive results indistributed computing, as a "blockage" in our tile assembly model is analogousto a crash failure in a distributed computing model.) we also define astrengthening of the "traditional" consensus problem, to make explicit anexpectation about consensus algorithms that is often implicit in distributedcomputing literature. we show that solution of this strengthened consensusproblem can be simulated by a two-dimensional tile assembly model only for twoprocesses, whereas a three-dimensional tile assembly model can simulate itssolution in a distributed system with any number of processes.

cs.dc cs.ne

nan

['sterling']

https://arxiv.org/abs/0902.3631