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on inversion formulas and fibonomial coefficients

0803.1393

a research problem for undergraduates and graduates is being posed as a capfor the prior antecedent regular discrete mathematics exercises. [here cap isnot necessarily cap=competitive access provider, though nevertheless ...] theobject of the cap problem of final interest i.e. array of fibonomialcoefficients and the issue of its combinatorial meaning is to be found ina.k.kwa\'sniewski's source papers. the cap problem number seven - still openedfor students has been placed on mathemagics page of the first author[http://ii.uwb.edu.pl/akk/dydaktyka/dyskr/dyskretna.htm]. the indicatoryreferences are to point at a part of the vast domain of the foundations ofcomputer science in arxiv affiliation noted as co.cs.dm. the presentation hasbeen verified in a tutor system of communication with a couple of intelligentstudents. the result is top secret.temporarily. [contact: wikipedia; theory ofcognitive development].

math.co cs.dm math.gm

nan

['kwaśniewski', 'krot-sieniawska']

https://arxiv.org/abs/0803.1393

dempster-shafer for anomaly detection

0803.1568

in this paper, we implement an anomaly detection system using thedempster-shafer method. using two standard benchmark problems we show that bycombining multiple signals it is possible to achieve better results than byusing a single signal. we further show that by applying this approach to areal-world email dataset the algorithm works for email worm detection.dempster-shafer can be a promising method for anomaly detection problems withmultiple features (data sources), and two or more classes.

cs.ne cs.ai cs.cr

nan

['chen', 'aickelin']

https://arxiv.org/abs/0803.1568

simulation optimization of the crossdock door assignment problem

0803.1576

the purpose of this report is to present the crossdock door assignmentproblem, which involves assigning destinations to outbound dock doors ofcrossdock centres such that travel distance by material handling equipment isminimized. we propose a two fold solution; simulation and optimization of thesimulation model simulation optimization. the novel aspect of our solutionapproach is that we intend to use simulation to derive a more realisticobjective function and use memetic algorithms to find an optimal solution. themain advantage of using memetic algorithms is that it combines a local searchwith genetic algorithms. the crossdock door assignment problem is a new domainapplication to memetic algorithms and it is yet unknown how it will perform.

cs.ne cs.ce

nan

['aickelin', 'adewunmi']

https://arxiv.org/abs/0803.1576

using intelligent agents to understand organisational behaviour

0803.1596

this paper introduces two ongoing research projects which seek to applycomputer modelling techniques in order to simulate human behaviour withinorganisations. previous research in other disciplines has suggested thatcomplex social behaviours are governed by relatively simple rules which, whenidentified, can be used to accurately model such processes using computertechnology. the broad objective of our research is to develop a similarcapability within organisational psychology.

cs.ne cs.ma

nan

['celia', 'clegg', 'robinson', 'siebers', 'aickelin', 'sprigg']

https://arxiv.org/abs/0803.1596

using intelligent agents to understand management practices and retail productivity

0803.1604

intelligent agents offer a new and exciting way of understanding the world ofwork. in this paper we apply agent-based modeling and simulation to investigatea set of problems in a retail context. specifically, we are working tounderstand the relationship between human resource management practices andretail productivity. despite the fact we are working within a relatively noveland complex domain, it is clear that intelligent agents could offer potentialfor fostering sustainable organizational capabilities in the future. theproject is still at an early stage. so far we have conducted a case study in auk department store to collect data and capture impressions about operationsand actors within departments. furthermore, based on our case study we havebuilt and tested our first version of a retail branch simulator which we willpresent in this paper.

cs.ne cs.ce cs.ma

nan

['siebers', 'aickelin', 'celia', 'clegg']

https://arxiv.org/abs/0803.1604

an agent-based simulation of in-store customer experiences

0803.1621

agent-based modelling and simulation offers a new and exciting way ofunderstanding the world of work. in this paper we describe the development ofan agent-based simulation model, designed to help to understand therelationship between human resource management practices and retailproductivity. we report on the current development of our simulation modelwhich includes new features concerning the evolution of customers over time. totest some of these features we have conducted a series of experiments dealingwith customer pool sizes, standard and noise reduction modes, and the spread ofthe word of mouth. our multi-disciplinary research team draws upon expertisefrom work psychologists and computer scientists. despite the fact we areworking within a relatively novel and complex domain, it is clear thatintelligent agents offer potential for fostering sustainable organisationalcapabilities in the future.

cs.ne cs.ce cs.ma

nan

['siebers', 'aickelin', 'celia', 'clegg']

https://arxiv.org/abs/0803.1621

genetic-algorithm seeding of idiotypic networks for mobile-robot navigation

0803.1626

robot-control designers have begun to exploit the properties of the humanimmune system in order to produce dynamic systems that can adapt to complex,varying, real-world tasks. jernes idiotypic-network theory has proved the mostpopular artificial-immune-system (ais) method for incorporation intobehaviour-based robotics, since idiotypic selection produces highly adaptiveresponses. however, previous efforts have mostly focused on evolving thenetwork connections and have often worked with a single, pre-engineered set ofbehaviours, limiting variability. this paper describes a method for encodingbehaviours as a variable set of attributes, and shows that when the encoding isused with a genetic algorithm (ga), multiple sets of diverse behaviours candevelop naturally and rapidly, providing much greater scope for flexiblebehaviour-selection. the algorithm is tested extensively with a simulatede-puck robot that navigates around a maze by tracking colour. results show thathighly successful behaviour sets can be generated within about 25 minutes, andthat much greater diversity can be obtained when multiple autonomouspopulations are used, rather than a single one.

cs.ne cs.ro

nan

['whitbrook', 'aickelin', 'garibaldi']

https://arxiv.org/abs/0803.1626

investigating a hybrid metaheuristic for job shop rescheduling

0803.1728

previous research has shown that artificial immune systems can be used toproduce robust schedules in a manufacturing environment. the main goal is todevelop building blocks (antibodies) of partial schedules that can be used toconstruct backup solutions (antigens) when disturbances occur duringproduction. the building blocks are created based upon underpinning ideas fromartificial immune systems and evolved using a genetic algorithm (phase i). eachpartial schedule (antibody) is assigned a fitness value and the best partialschedules are selected to be converted into complete schedules (antigens). wefurther investigate whether simulated annealing and the great deluge algorithmcan improve the results when hybridised with our artificial immune system(phase ii). we use ten fixed solutions as our target and measure how well wecover these specific scenarios.

cs.ne cs.ce

10.1007/978-3-540-76931-6_31

['abdullah', 'aickelin', 'burke', 'din', 'qu']

https://arxiv.org/abs/0803.1728

an investigation of the sequential sampling method for crossdocking simulation output variance reduction

0803.1985

this paper investigates the reduction of variance associated with asimulation output performance measure, using the sequential sampling methodwhile applying minimum simulation replications, for a class of jit (just intime) warehousing system called crossdocking. we initially used the sequentialsampling method to attain a desired 95% confidence interval half width ofplus/minus 0.5 for our chosen performance measure (total usage cost, given themean maximum level of 157,000 pounds and a mean minimum level of 149,000pounds). from our results, we achieved a 95% confidence interval half width ofplus/minus 2.8 for our chosen performance measure (total usage cost, with anaverage mean value of 115,000 pounds). however, the sequential sampling methodrequires a huge number of simulation replications to reduce variance for oursimulation output value to the target level. arena (version 11) simulationsoftware was used to conduct this study.

cs.ne cs.ce

nan

['adewunmi', 'aickelin', 'byrne']

https://arxiv.org/abs/0803.1985

improved squeaky wheel optimisation for driver scheduling

0803.1993

this paper presents a technique called improved squeaky wheel optimisationfor driver scheduling problems. it improves the original squeaky wheeloptimisations effectiveness and execution speed by incorporating two additionalsteps of selection and mutation which implement evolution within a singlesolution. in the iswo, a cycle ofanalysis-selection-mutation-prioritization-construction continues untilstopping conditions are reached. the analysis step first computes the fitnessof a current solution to identify troublesome components. the selection stepthen discards these troublesome components probabilistically by using thefitness measure, and the mutation step follows to further discard a smallnumber of components at random. after the above steps, an input solutionbecomes partial and thus the resulting partial solution needs to be repaired.the repair is carried out by using the prioritization step to first producepriorities that determine an order by which the following construction stepthen schedules the remaining components. therefore, the optimisation in theiswo is achieved by solution disruption, iterative improvement and an iterativeconstructive repair process performed. encouraging experimental results arereported.

cs.ne cs.ce

10.1007/11844297_19

['aickelin', 'burke', 'li']

https://arxiv.org/abs/0803.1993

the application of bayesian optimization and classifier systems in nurse scheduling

0803.1994

two ideas taken from bayesian optimization and classifier systems arepresented for personnel scheduling based on choosing a suitable scheduling rulefrom a set for each persons assignment. unlike our previous work of usinggenetic algorithms whose learning is implicit, the learning in both approachesis explicit, i.e. we are able to identify building blocks directly. to achievethis target, the bayesian optimization algorithm builds a bayesian network ofthe joint probability distribution of the rules used to construct solutions,while the adapted classifier system assigns each rule a strength value that isconstantly updated according to its usefulness in the current situation.computational results from 52 real data instances of nurse schedulingdemonstrate the success of both approaches. it is also suggested that thelearning mechanism in the proposed approaches might be suitable for otherscheduling problems.

cs.ne cs.ce

10.1007/b100601

['li', 'aickelin']

https://arxiv.org/abs/0803.1994

danger theory: the link between ais and ids?

0803.1997

we present ideas about creating a next generation intrusion detection systembased on the latest immunological theories. the central challenge with computersecurity is determining the difference between normal and potentially harmfulactivity. for half a century, developers have protected their systems by codingrules that identify and block specific events. however, the nature of currentand future threats in conjunction with ever larger it systems urgently requiresthe development of automated and adaptive defensive tools. a promising solutionis emerging in the form of artificial immune systems. the human immune systemcan detect and defend against harmful and previously unseen invaders, so can wenot build a similar intrusion detection system for our computers.

cs.ne cs.ai cs.cr

10.1007/b12020

['aickelin', 'bentley', 'cayzer', 'jungwon', 'mcleod']

https://arxiv.org/abs/0803.1997

constant-rank codes and their connection to constant-dimension codes

0803.2262

constant-dimension codes have recently received attention due to theirsignificance to error control in noncoherent random linear network coding. whatthe maximal cardinality of any constant-dimension code with finite dimensionand minimum distance is and how to construct the optimal constant-dimensioncode (or codes) that achieves the maximal cardinality both remain open researchproblems. in this paper, we introduce a new approach to solving these twoproblems. we first establish a connection between constant-rank codes andconstant-dimension codes. via this connection, we show that optimalconstant-dimension codes correspond to optimal constant-rank codes overmatrices with sufficiently many rows. as such, the two aforementioned problemsare equivalent to determining the maximum cardinality of constant-rank codesand to constructing optimal constant-rank codes, respectively. to this end, wethen derive bounds on the maximum cardinality of a constant-rank code with agiven minimum rank distance, propose explicit constructions of optimal orasymptotically optimal constant-rank codes, and establish asymptotic bounds onthe maximum rate of a constant-rank code.

cs.it math.it

nan

['gadouleau', 'yan']

https://arxiv.org/abs/0803.2262

enhanced direct and indirect genetic algorithm approaches for a mall layout and tenant selection problem

0803.2957

during our earlier research, it was recognised that in order to be successfulwith an indirect genetic algorithm approach using a decoder, the decoder has tostrike a balance between being an optimiser in its own right and findingfeasible solutions. previously this balance was achieved manually. here weextend this by presenting an automated approach where the genetic algorithmitself, simultaneously to solving the problem, sets weights to balance thecomponents out. subsequently we were able to solve a complex and non-linearscheduling problem better than with a standard direct genetic algorithmimplementation.

cs.ne cs.ce

10.1023/a:1016536623961,

['aickelin', 'dowsland']

https://arxiv.org/abs/0803.2957

an indirect genetic algorithm for set covering problems

0803.2965

this paper presents a new type of genetic algorithm for the set coveringproblem. it differs from previous evolutionary approaches first because it isan indirect algorithm, i.e. the actual solutions are found by an externaldecoder function. the genetic algorithm itself provides this decoder withpermutations of the solution variables and other parameters. second, it will beshown that results can be further improved by adding another indirectoptimisation layer. the decoder will not directly seek out low cost solutionsbut instead aims for good exploitable solutions. these are then post optimisedby another hill-climbing algorithm. although seemingly more complicated, wewill show that this three-stage approach has advantages in terms of solutionquality, speed and adaptability to new types of problems over more directapproaches. extensive computational results are presented and compared to thelatest evolutionary and other heuristic approaches to the same data instances.

cs.ne cs.ai

10.1057/palgrave.jors.2601317

['aickelin']

https://arxiv.org/abs/0803.2965

on the application of hierarchical coevolutionary genetic algorithms: recombination and evaluation partners

0803.2966

this paper examines the use of a hierarchical coevolutionary geneticalgorithm under different partnering strategies. cascading clusters ofsub-populations are built from the bottom up, with higher-level sub-populationsoptimising larger parts of the problem. hence higher-level sub-populationspotentially search a larger search space with a lower resolution whilstlower-level sub-populations search a smaller search space with a higherresolution. the effects of different partner selection schemes amongst thesub-populations on solution quality are examined for two constrainedoptimisation problems. we examine a number of recombination partneringstrategies in the construction of higher-level individuals and a number ofrelated schemes for evaluating sub-solutions. it is shown that partneringstrategies that exploit problem-specific knowledge are superior and can counterinappropriate (sub)fitness measurements.

cs.ne cs.ai

nan

['aickelin', 'bull']

https://arxiv.org/abs/0803.2966

building better nurse scheduling algorithms

0803.2967

the aim of this research is twofold: firstly, to model and solve a complexnurse scheduling problem with an integer programming formulation andevolutionary algorithms. secondly, to detail a novel statistical method ofcomparing and hence building better scheduling algorithms by identifyingsuccessful algorithm modifications. the comparison method captures the resultsof algorithms in a single figure that can then be compared using traditionalstatistical techniques. thus, the proposed method of comparing algorithms is anobjective procedure designed to assist in the process of improving analgorithm. this is achieved even when some results are non-numeric or missingdue to infeasibility. the final algorithm outperforms all previous evolutionaryalgorithms, which relied on human expertise for modification.

cs.ne cs.ce

10.1023/b:anor.0000019103.31340.a6

['aickelin', 'white']

https://arxiv.org/abs/0803.2967

an indirect genetic algorithm for a nurse scheduling problem

0803.2969

this paper describes a genetic algorithms approach to a manpower-schedulingproblem arising at a major uk hospital. although genetic algorithms have beensuccessfully used for similar problems in the past, they always had to overcomethe limitations of the classical genetic algorithms paradigm in handling theconflict between objectives and constraints. the approach taken here is to usean indirect coding based on permutations of the nurses, and a heuristic decoderthat builds schedules from these permutations. computational experiments basedon 52 weeks of live data are used to evaluate three different decoders withvarying levels of intelligence, and four well-known crossover operators.results are further enhanced by introducing a hybrid crossover operator and bymaking use of simple bounds to reduce the size of the solution space. theresults reveal that the proposed algorithm is able to find high qualitysolutions and is both faster and more flexible than a recently published tabusearch approach.

cs.ne cs.ce

10.1016/s0305-0548(03)00034-0

['aickelin', 'dowsland']

https://arxiv.org/abs/0803.2969

a recommender system based on idiotypic artificial immune networks

0803.2970

the immune system is a complex biological system with a highly distributed,adaptive and self-organising nature. this paper presents an artificial immunesystem (ais) that exploits some of these characteristics and is applied to thetask of film recommendation by collaborative filtering (cf). natural evolutionand in particular the immune system have not been designed for classicaloptimisation. however, for this problem, we are not interested in finding asingle optimum. rather we intend to identify a sub-set of good matches on whichrecommendations can be based. it is our hypothesis that an ais built on twocentral aspects of the biological immune system will be an ideal candidate toachieve this: antigen-antibody interaction for matching and idiotypicantibody-antibody interaction for diversity. computational results arepresented in support of this conjecture and compared to those found by other cftechniques.

cs.ne cs.ai

10.1007/s10852-004-5336-7

['cayzer', 'aickelin']

https://arxiv.org/abs/0803.2970

rule generalisation in intrusion detection systems using snort

0803.2973

intrusion detection systems (ids)provide an important layer of security forcomputer systems and networks, and are becoming more and more necessary asreliance on internet services increases and systems with sensitive data aremore commonly open to internet access. an ids responsibility is to detectsuspicious or unacceptable system and network activity and to alert a systemsadministrator to this activity. the majority of ids use a set of signaturesthat define what suspicious traffic is, and snort is one popular and activelydeveloping open-source ids that uses such a set of signatures known as snortrules. our aim is to identify a way in which snort could be developed furtherby generalising rules to identify novel attacks. in particular, we attempted torelax and vary the conditions and parameters of current snort rules, using asimilar approach to classic rule learning operators such as generalisation andspecialisation. we demonstrate the effectiveness of our approach throughexperiments with standard datasets and show that we are able to detectpreviously undeleted variants of various attacks. we conclude by discussing thegeneral effectiveness and appropriateness of generalisation in snort based idsrule processing.

cs.ne cs.cr

10.1504/ijesdf.2007.013596,

['aickelin', 'twycross', 'hesketh-roberts']

https://arxiv.org/abs/0803.2973

an estimation of distribution algorithm for nurse scheduling

0803.2975

schedules can be built in a similar way to a human scheduler by using a setof rules that involve domain knowledge. this paper presents an estimation ofdistribution algorithm (eda) for the nurse scheduling problem, which involveschoosing a suitable scheduling rule from a set for the assignment of eachnurse. unlike previous work that used genetic algorithms (ga) to implementimplicit learning, the learning in the proposed algorithm is explicit, i.e. weidentify and mix building blocks directly. the eda is applied to implement suchexplicit learning by building a bayesian network of the joint distribution ofsolutions. the conditional probability of each variable in the network iscomputed according to an initial set of promising solutions. subsequently, eachnew instance for each variable is generated by using the correspondingconditional probabilities, until all variables have been generated, i.e. in ourcase, a new rule string has been obtained. another set of rule strings will begenerated in this way, some of which will replace previous strings based onfitness selection. if stopping conditions are not met, the conditionalprobabilities for all nodes in the bayesian network are updated again using thecurrent set of promising rule strings. computational results from 52 real datainstances demonstrate the success of this approach. it is also suggested thatthe learning mechanism in the proposed approach might be suitable for otherscheduling problems.

cs.ne cs.ce

10.1007/s10479-007-0214-0

['aickelin', 'li']

https://arxiv.org/abs/0803.2975

idiotypic immune networks in mobile robot control

0803.2981

jerne's idiotypic network theory postulates that the immune response involvesinter-antibody stimulation and suppression as well as matching to antigens. thetheory has proved the most popular artificial immune system (ais) model forincorporation into behavior-based robotics but guidelines for implementingidiotypic selection are scarce. furthermore, the direct effects of employingthe technique have not been demonstrated in the form of a comparison withnon-idiotypic systems. this paper aims to address these issues. a method forintegrating an idiotypic ais network with a reinforcement learning basedcontrol system (rl) is described and the mechanisms underlying antibodystimulation and suppression are explained in detail. some hypotheses thataccount for the network advantage are put forward and tested using threesystems with increasing idiotypic complexity. the basic rl, a simplified hybridais-rl that implements idiotypic selection independently of derivedconcentration levels and a full hybrid ais-rl scheme are examined. the test bedtakes the form of a simulated pioneer robot that is required to navigatethrough maze worlds detecting and tracking door markers.

cs.ne cs.ai cs.ro

10.1109/tsmcb.2007.907334

['whitbrook', 'aickelin', 'garibaldi']

https://arxiv.org/abs/0803.2981

robustness and regularization of support vector machines

0803.3490

we consider regularized support vector machines (svms) and show that they areprecisely equivalent to a new robust optimization formulation. we show thatthis equivalence of robust optimization and regularization has implications forboth algorithms, and analysis. in terms of algorithms, the equivalence suggestsmore general svm-like algorithms for classification that explicitly build inprotection to noise, and at the same time control overfitting. on the analysisfront, the equivalence of robustness and regularization, provides a robustoptimization interpretation for the success of regularized svms. we use thethis new robustness interpretation of svms to give a new proof of consistencyof (kernelized) svms, thus establishing robustness as the reason regularizedsvms generalize well.

cs.lg cs.ai

nan

['xu', 'caramanis', 'mannor']

https://arxiv.org/abs/0803.3490

a component based heuristic search method with adaptive perturbations for hospital personnel scheduling

0803.3900

nurse rostering is a complex scheduling problem that affects hospitalpersonnel on a daily basis all over the world. this paper presents a newcomponent-based approach with adaptive perturbations, for a nurse schedulingproblem arising at a major uk hospital. the main idea behind this technique isto decompose a schedule into its components (i.e. the allocated shift patternof each nurse), and then mimic a natural evolutionary process on thesecomponents to iteratively deliver better schedules. the worthiness of allcomponents in the schedule has to be continuously demonstrated in order forthem to remain there. this demonstration employs a dynamic evaluation functionwhich evaluates how well each component contributes towards the finalobjective. two perturbation steps are then applied: the first perturbationeliminates a number of components that are deemed not worthy to stay in thecurrent schedule; the second perturbation may also throw out, with a low levelof probability, some worthy components. the eliminated components arereplenished with new ones using a set of constructive heuristics using localoptimality criteria. computational results using 52 data instances demonstratethe applicability of the proposed approach in solving real-world problems.

cs.ne cs.ce

nan

['li', 'aickelin', 'burke']

https://arxiv.org/abs/0803.3900

artificial immune systems tutorial

0803.3912

the biological immune system is a robust, complex, adaptive system thatdefends the body from foreign pathogens. it is able to categorize all cells (ormolecules) within the body as self-cells or non-self cells. it does this withthe help of a distributed task force that has the intelligence to take actionfrom a local and also a global perspective using its network of chemicalmessengers for communication. there are two major branches of the immunesystem. the innate immune system is an unchanging mechanism that detects anddestroys certain invading organisms, whilst the adaptive immune system respondsto previously unknown foreign cells and builds a response to them that canremain in the body over a long period of time. this remarkable informationprocessing biological system has caught the attention of computer science inrecent years. a novel computational intelligence technique, inspired byimmunology, has emerged, called artificial immune systems. several conceptsfrom the immune have been extracted and applied for solution to real worldscience and engineering problems. in this tutorial, we briefly describe theimmune system metaphors that are relevant to existing artificial immune systemsmethods. we will then show illustrative real-world problems suitable forartificial immune systems and give a step-by-step algorithm walkthrough for onesuch problem. a comparison of the artificial immune systems to other well-knownalgorithms, areas for future work, tips & tricks and a list of resources willround this tutorial off. it should be noted that as artificial immune systemsis still a young and evolving field, there is not yet a fixed algorithmtemplate and hence actual implementations might differ somewhat from time totime and from those examples given here.

cs.ne cs.ai cs.ma

nan

['aickelin', 'dasgupta']

https://arxiv.org/abs/0803.3912

reflective visualization and verbalization of unconscious preference

0803.4074

a new method is presented, that can help a person become aware of his or herunconscious preferences, and convey them to others in the form of verbalexplanation. the method combines the concepts of reflection, visualization, andverbalization. the method was tested in an experiment where the unconsciouspreferences of the subjects for various artworks were investigated. in theexperiment, two lessons were learned. the first is that it helps the subjectsbecome aware of their unconscious preferences to verbalize weak preferences ascompared with strong preferences through discussion over preference diagrams.the second is that it is effective to introduce an adjustable factor intovisualization to adapt to the differences in the subjects and to foster theirmutual understanding.

cs.ai

10.1504/ijaip.2010.030531

['maeno', 'ohsawa']

https://arxiv.org/abs/0803.4074

optimization of enzymatic biochemical logic for noise reduction and scalability: how many biocomputing gates can be interconnected in a circuit?

0803.4197

we report an experimental evaluation of the "input-output surface" for abiochemical and gate. the obtained data are modeled within the rate-equationapproach, with the aim to map out the gate function and cast it in the languageof logic variables appropriate for analysis of boolean logic for scalability.in order to minimize "analog" noise, we consider a theoretical approach fordetermining an optimal set for the process parameters to minimize "analog"noise amplification for gate concatenation. we establish that under optimizedconditions, presently studied biochemical gates can be concatenated for up toorder 10 processing steps. beyond that, new paradigms for avoiding noisebuild-up will have to be developed. we offer a general discussion of the ideasand possible future challenges for both experimental and theoretical researchfor advancing scalable biochemical computing.

q-bio.mn cond-mat.other cond-mat.soft cs.cc q-bio.bm q-bio.ot q-bio.qm quant-ph

10.1021/jp802673q

['privman', 'strack', 'solenov', 'pita', 'katz']

https://arxiv.org/abs/0803.4197

cryptanalysis of two mceliece cryptosystems based on quasi-cyclic codes

0804.0409

we cryptanalyse here two variants of the mceliece cryptosystem based onquasi-cyclic codes. both aim at reducing the key size by restricting the publicand secret generator matrices to be in quasi-cyclic form. the first variantconsiders subcodes of a primitive bch code. we prove that this variant is notsecure by finding and solving a linear system satisfied by the entries of thesecret permutation matrix. the other variant uses quasi-cyclic low density parity-check codes. thisscheme was devised to be immune against general attacks working for mceliecetype cryptosystems based on low density parity-check codes by choosing in themceliece scheme more general one-to-one mappings than permutation matrices. wesuggest here a structural attack exploiting the quasi-cyclic structure of thecode and a certain weakness in the choice of the linear transformations thathide the generator matrix of the code. our analysis shows that with highprobability a parity-check matrix of a punctured version of the secret code canbe recovered in cubic time complexity in its length. the completereconstruction of the secret parity-check matrix of the quasi-cyclic lowdensity parity-check codes requires the search of codewords of low weight whichcan be done with about $2^{37}$ operations for the specific parametersproposed.

cs.cr cs.dm

nan

['otmani', 'tillich', 'dallot']

https://arxiv.org/abs/0804.0409

bayesian optimisation algorithm for nurse scheduling

0804.0524

our research has shown that schedules can be built mimicking a humanscheduler by using a set of rules that involve domain knowledge. this chapterpresents a bayesian optimization algorithm (boa) for the nurse schedulingproblem that chooses such suitable scheduling rules from a set for each nursesassignment. based on the idea of using probabilistic models, the boa builds abayesian network for the set of promising solutions and samples these networksto generate new candidate solutions. computational results from 52 real datainstances demonstrate the success of this approach. it is also suggested thatthe learning mechanism in the proposed algorithm may be suitable for otherscheduling problems.

cs.ne cs.ce

10.1007/978-3-540-34954-9_14

['li', 'aickelin']

https://arxiv.org/abs/0804.0524

an artificial immune system as a recommender system for web sites

0804.0573

artificial immune systems have been used successfully to build recommendersystems for film databases. in this research, an attempt is made to extend thisidea to web site recommendation. a collection of more than 1000 individuals webprofiles (alternatively called preferences / favourites / bookmarks file) willbe used. urls will be classified using the dmoz (directory mozilla) database ofthe open directory project as our ontology. this will then be used as the datafor the artificial immune systems rather than the actual addresses. the firstattempt will involve using a simple classification code number coupled with thenumber of pages within that classification code. however, this implementationdoes not make use of the hierarchical tree-like structure of dmoz.consideration will then be given to the construction of a similarity measurefor web profiles that makes use of this hierarchical information to build abetter-informed artificial immune system.

cs.ne cs.ai

nan

['morrison', 'aickelin']

https://arxiv.org/abs/0804.0573

explicit learning: an effort towards human scheduling algorithms

0804.0580

scheduling problems are generally np-hard combinatorial problems, and a lotof research has been done to solve these problems heuristically. however, mostof the previous approaches are problem-specific and research into thedevelopment of a general scheduling algorithm is still in its infancy. mimicking the natural evolutionary process of the survival of the fittest,genetic algorithms (gas) have attracted much attention in solving difficultscheduling problems in recent years. some obstacles exist when using gas: thereis no canonical mechanism to deal with constraints, which are commonly met inmost real-world scheduling problems, and small changes to a solution aredifficult. to overcome both difficulties, indirect approaches have beenpresented (in [1] and [2]) for nurse scheduling and driver scheduling, wheregas are used by mapping the solution space, and separate decoding routines thenbuild solutions to the original problem.

cs.ne cs.ai

nan

['li', 'aickelin']

https://arxiv.org/abs/0804.0580

a memetic algorithm for the generalized traveling salesman problem

0804.0722

the generalized traveling salesman problem (gtsp) is an extension of thewell-known traveling salesman problem. in gtsp, we are given a partition ofcities into groups and we are required to find a minimum length tour thatincludes exactly one city from each group. the recent studies on this subjectconsider different variations of a memetic algorithm approach to the gtsp. theaim of this paper is to present a new memetic algorithm for gtsp with apowerful local search procedure. the experiments show that the proposedalgorithm clearly outperforms all of the known heuristics with respect to bothsolution quality and running time. while the other memetic algorithms weredesigned only for the symmetric gtsp, our algorithm can solve both symmetricand asymmetric instances.

cs.ds

10.1007/s11047-009-9111-6

['gutin', 'karapetyan']

https://arxiv.org/abs/0804.0722

generalized traveling salesman problem reduction algorithms

0804.0735

the generalized traveling salesman problem (gtsp) is an extension of thewell-known traveling salesman problem. in gtsp, we are given a partition ofcities into groups and we are required to find a minimum length tour thatincludes exactly one city from each group. the aim of this paper is to presenta problem reduction algorithm that deletes redundant vertices and edges,preserving the optimal solution. the algorithm's running time is o(n^3) in theworst case, but it is significantly faster in practice. the algorithm hasreduced the problem size by 15-20% on average in our experiments and this hasdecreased the solution time by 10-60% for each of the considered solvers.

cs.ds

nan

['gutin', 'karapetyan']

https://arxiv.org/abs/0804.0735

immune system approaches to intrusion detection - a review

0804.1266

the use of artificial immune systems in intrusion detection is an appealingconcept for two reasons. firstly, the human immune system provides the humanbody with a high level of protection from invading pathogens, in a robust,self-organised and distributed manner. secondly, current techniques used incomputer security are not able to cope with the dynamic and increasinglycomplex nature of computer systems and their security. it is hoped thatbiologically inspired approaches in this area, including the use ofimmune-based systems will be able to meet this challenge. here we review thealgorithms used, the development of the systems and the outcome of theirimplementation. we provide an introduction and analysis of the key developmentswithin this field, in addition to making suggestions for future research.

cs.ne cs.cr

10.1007/s11047-006-9026-4

['kim', 'bentley', 'aickelin', 'greensmith', 'tedesco', 'twycross']

https://arxiv.org/abs/0804.1266

data reduction in intrusion alert correlation

0804.1281

network intrusion detection sensors are usually built around low level modelsof network traffic. this means that their output is of a similarly low leveland as a consequence, is difficult to analyze. intrusion alert correlation isthe task of automating some of this analysis by grouping related alertstogether. attack graphs provide an intuitive model for such analysis.unfortunately alert flooding attacks can still cause a loss of service onsensors, and when performing attack graph correlation, there can be a largenumber of extraneous alerts included in the output graph. this obscures thefine structure of genuine attacks and makes them more difficult for humanoperators to discern. this paper explores modified correlation algorithms whichattempt to minimize the impact of this attack.

cs.cr cs.ne

nan

['tedesco', 'aickelin']

https://arxiv.org/abs/0804.1281

mechanizing the metatheory of lf

0804.1667

lf is a dependent type theory in which many other formal systems can beconveniently embedded. however, correct use of lf relies on nontrivialmetatheoretic developments such as proofs of correctness of decision proceduresfor lf's judgments. although detailed informal proofs of these properties havebeen published, they have not been formally verified in a theorem prover. wehave formalized these properties within isabelle/hol using the nominal datatypepackage, closely following a recent article by harper and pfenning. in theprocess, we identified and resolved a gap in one of the proofs and a smallnumber of minor lacunae in others. we also formally derive a version of thetype checking algorithm from which isabelle/hol can generate executable code.besides its intrinsic interest, our formalization provides a foundation forstudying the adequacy of lf encodings, the correctness of twelf-stylemetatheoretic reasoning, and the metatheory of extensions to lf.

cs.lo

nan

['urban', 'cheney', 'berghofer']

https://arxiv.org/abs/0804.1667

on affine usages in signal-based communication

0804.1729

we describe a type system for a synchronous pi-calculus formalising thenotion of affine usage in signal-based communication. in particular, weidentify a limited number of usages that preserve affinity and that can becomposed. as a main application of the resulting system, we show that typableprograms are deterministic.

cs.lo

nan

['amadio', 'dogguy']

https://arxiv.org/abs/0804.1729

necessary and sufficient conditions on sparsity pattern recovery

0804.1839

the problem of detecting the sparsity pattern of a k-sparse vector in r^nfrom m random noisy measurements is of interest in many areas such as systemidentification, denoising, pattern recognition, and compressed sensing. thispaper addresses the scaling of the number of measurements m, with signaldimension n and sparsity-level nonzeros k, for asymptotically-reliabledetection. we show a necessary condition for perfect recovery at any given snrfor all algorithms, regardless of complexity, is m = omega(k log(n-k))measurements. conversely, it is shown that this scaling of omega(k log(n-k))measurements is sufficient for a remarkably simple ``maximum correlation''estimator. hence this scaling is optimal and does not require moresophisticated techniques such as lasso or matching pursuit. the constants forboth the necessary and sufficient conditions are precisely defined in terms ofthe minimum-to-average ratio of the nonzero components and the snr. thenecessary condition improves upon previous results for maximum likelihoodestimation. for lasso, it also provides a necessary condition at any snr andfor low snr improves upon previous work. the sufficient condition provides thefirst asymptotically-reliable detection guarantee at finite snr.

cs.it math.it

10.1109/tit.2009.2032726

['fletcher', 'rangan', 'goyal']

https://arxiv.org/abs/0804.1839

towards physarum robots: computing and manipulating on water surface

0804.2036

plasmodium of physarym polycephalum is an ideal biological substrate forimplementing concurrent and parallel computation, including combinatorialgeometry and optimization on graphs. we report results of scoping experimentson physarum computing in conditions of minimal friction, on the water surface.we show that plasmodium of physarum is capable for computing a basic spanningtrees and manipulating of light-weight objects. we speculate that our resultspave the pathways towards design and implementation of amorphous biologicalrobots.

cs.ro cs.ai

10.1016/s1672-6529(08)60180-8

['adamatzky']

https://arxiv.org/abs/0804.2036

interlace polynomials: enumeration, unimodality, and connections to codes

0804.2576

the interlace polynomial q was introduced by arratia, bollobas, and sorkin.it encodes many properties of the orbit of a graph under edge localcomplementation (elc). the interlace polynomial q, introduced by aigner and vander holst, similarly contains information about the orbit of a graph underlocal complementation (lc). we have previously classified lc and elc orbits,and now give an enumeration of the corresponding interlace polynomials of allgraphs of order up to 12. an enumeration of all circle graphs of order up to 12is also given. we show that there exist graphs of all orders greater than 9with interlace polynomials q whose coefficient sequences are non-unimodal,thereby disproving a conjecture by arratia et al. we have verified that forgraphs of order up to 12, all polynomials q have unimodal coefficients. it hasbeen shown that lc and elc orbits of graphs correspond to equivalence classesof certain error-correcting codes and quantum states. we show that theproperties of these codes and quantum states are related to properties of theassociated interlace polynomials.

math.co cs.it math.it

10.1016/j.dam.2009.11.011

['danielsen', 'parker']

https://arxiv.org/abs/0804.2576

towards a stable definition of kolmogorov-chaitin complexity

0804.3459

although information content is invariant up to an additive constant, therange of possible additive constants applicable to programming languages is solarge that in practice it plays a major role in the actual evaluation of k(s),the kolmogorov-chaitin complexity of a string s. some attempts have been madeto arrive at a framework stable enough for a concrete definition of k,independent of any constant under a programming language, by appealing to the"naturalness" of the language in question. the aim of this paper is to presentan approach to overcome the problem by looking at a set of models ofcomputation converging in output probability distribution such that that"naturalness" can be inferred, thereby providing a framework for a stabledefinition of k under the set of convergent models of computation.

cs.it cs.cc math.it

nan

['delahaye', 'zenil']

https://arxiv.org/abs/0804.3459

a non-distillability criterion for secret correlations

0804.4523

within entanglement theory there are criteria which certify that some quantumstates cannot be distilled into pure entanglement. an example is the positivepartial transposition criterion. here we present, for the first time, theanalogous thing for secret correlations. we introduce a computable criterionwhich certifies that a probability distribution between two honest parties andan eavesdropper cannot be (asymptotically) distilled into a secret key. theexistence of non-distillable correlations with positive secrecy cost, alsoknown as bound information, is an open question. this criterion may be the keyfor finding bound information. however, if it turns out that this criteriondoes not detect bound information, then, a very interesting consequencefollows: any distribution with positive secrecy cost can increase the secrecycontent of another distribution. in other words, all correlations with positivesecrecy cost constitute a useful resource.

quant-ph cs.cr

nan

['masanes', 'winter']

https://arxiv.org/abs/0804.4523

alternating automata on data trees and xpath satisfiability

0805.0330

a data tree is an unranked ordered tree whose every node is labelled by aletter from a finite alphabet and an element ("datum") from an infinite set,where the latter can only be compared for equality. the article considersalternating automata on data trees that can move downward and rightward, andhave one register for storing data. the main results are that nonemptiness overfinite data trees is decidable but not primitive recursive, and thatnonemptiness of safety automata is decidable but not elementary. the proofs usenondeterministic tree automata with faulty counters. allowing upward moves,leftward moves, or two registers, each causes undecidability. as corollaries,decidability is obtained for two data-sensitive fragments of the xpath querylanguage.

cs.lo cs.db cs.fl

nan

['jurdzinski', 'lazic']

https://arxiv.org/abs/0805.0330

decoding generalized concatenated codes using interleaved reed-solomon codes

0805.0501

generalized concatenated codes are a code construction consisting of a numberof outer codes whose code symbols are protected by an inner code. as outercodes, we assume the most frequently used reed-solomon codes; as inner code, weassume some linear block code which can be decoded up to half its minimumdistance. decoding up to half the minimum distance of generalized concatenatedcodes is classically achieved by the blokh-zyablov-dumer algorithm, whichiteratively decodes by first using the inner decoder to get an estimate of theouter code words and then using an outer error/erasure decoder with a varyingnumber of erasures determined by a set of pre-calculated thresholds. in thispaper, a modified version of the blokh-zyablov-dumer algorithm is proposed,which exploits the fact that a number of outer reed-solomon codes with averageminimum distance d can be grouped into one single interleaved reed-solomon codewhich can be decoded beyond d/2. this allows to skip a number of decodingiterations on the one hand and to reduce the complexity of each decodingiteration significantly - while maintaining the decoding performance - on theother.

cs.it math.it

10.1109/isit.2008.4595300

['senger', 'sidorenko', 'bossert', 'zyablov']

https://arxiv.org/abs/0805.0501

upper bounds for alpha-domination parameters

0805.0612

in this paper, we provide a new upper bound for the alpha-domination number.this result generalises the well-known caro-roditty bound for the dominationnumber of a graph. the same probabilistic construction is used to generaliseanother well-known upper bound for the classical domination in graphs. we alsoprove similar upper bounds for the alpha-rate domination number, which combinesthe concepts of alpha-domination and k-tuple domination.

math.co cs.dm

10.1007/s00373-009-0864-6

['gagarin', 'poghosyan', 'zverovich']

https://arxiv.org/abs/0805.0612

order to disorder transitions in hybrid intelligent systems: a hatch to the interactions of nations -governments

0805.0642

in this study, under general frame of many connected intelligent particlessystems (macips), we reproduce two new simple subsets of such intelligentcomplex network, namely hybrid intelligent systems, involved a few prominentintelligent computing and approximate reasoning methods: self organizingfeature map (som), neuro-fuzzy inference system and rough set theory (rst).over this, we show how our algorithms can be construed as a linkage ofgovernment-society interaction, where government catches various fashions ofbehavior: solid (absolute) or flexible. so, transition of such society, bychanging of connectivity parameters (noise) from order to disorder is inferred.add to this, one may find an indirect mapping among financial systems andeventual market fluctuations with macips.

cs.ai cs.it math.it

nan

['owladeghaffari']

https://arxiv.org/abs/0805.0642

quasiperiodic and lyndon episturmian words

0805.0730

recently the second two authors characterized quasiperiodic sturmian words,proving that a sturmian word is non-quasiperiodic if and only if it is aninfinite lyndon word. here we extend this study to episturmian words (a naturalgeneralization of sturmian words) by describing all the quasiperiods of anepisturmian word, which yields a characterization of quasiperiodic episturmianwords in terms of their "directive words". even further, we establish acomplete characterization of all episturmian words that are lyndon words. ourmain results show that, unlike the sturmian case, there is a much wider classof episturmian words that are non-quasiperiodic, besides those that areinfinite lyndon words. our key tools are morphisms and directive words, inparticular "normalized" directive words, which we introduced in an earlierpaper. also of importance is the use of "return words" to characterizequasiperiodic episturmian words, since such a method could be useful in othercontexts.

math.co cs.dm

10.1016/j.tcs.2008.09.056

['glen', 'levé', 'richomme']

https://arxiv.org/abs/0805.0730

submodular approximation: sampling-based algorithms and lower bounds

0805.1071

we introduce several generalizations of classical computer science problemsobtained by replacing simpler objective functions with general submodularfunctions. the new problems include submodular load balancing, whichgeneralizes load balancing or minimum-makespan scheduling, submodular sparsestcut and submodular balanced cut, which generalize their respective graph cutproblems, as well as submodular function minimization with a cardinality lowerbound. we establish upper and lower bounds for the approximability of theseproblems with a polynomial number of queries to a function-value oracle. theapproximation guarantees for most of our algorithms are of the order ofsqrt(n/ln n). we show that this is the inherent difficulty of the problems byproving matching lower bounds. we also give an improved lower bound for theproblem of approximately learning a monotone submodular function. in addition,we present an algorithm for approximately learning submodular functions withspecial structure, whose guarantee is close to the lower bound. although quiterestrictive, the class of functions with this structure includes the ones thatare used for lower bounds both by us and in previous work. this demonstratesthat if there are significantly stronger lower bounds for this problem, theyrely on more general submodular functions.

cs.ds

nan

['svitkina', 'fleischer']

https://arxiv.org/abs/0805.1071

greedy forwarding in dynamic scale-free networks embedded in hyperbolic metric spaces

0805.1266

we show that complex (scale-free) network topologies naturally emerge fromhyperbolic metric spaces. hyperbolic geometry facilitates maximally efficientgreedy forwarding in these networks. greedy forwarding is topology-oblivious.nevertheless, greedy packets find their destinations with 100% probabilityfollowing almost optimal shortest paths. this remarkable efficiency sustainseven in highly dynamic networks. our findings suggest that forwardinginformation through complex networks, such as the internet, is possible withoutthe overhead of existing routing protocols, and may also find practicalapplications in overlay networks for tasks such as application-level routing,information sharing, and data distribution.

cond-mat.stat-mech cond-mat.dis-nn cs.ni physics.soc-ph

10.1109/infcom.2010.5462131

['papadopoulos', 'krioukov', 'boguna', 'vahdat']

https://arxiv.org/abs/0805.1266

physically-relativized church-turing hypotheses

0805.1292

we turn `the' church-turing hypothesis from an ambiguous source ofsensational speculations into a (collection of) sound and well-definedscientific problem(s): examining recent controversies, and causes for misunderstanding, concerningthe state of the church-turing hypothesis (cth), suggests to study the cthrelative to an arbitrary but specific physical theory--rather than vaguelyreferring to ``nature'' in general. to this end we combine (and compare)physical structuralism with (models of computation in) complexity theory. thebenefit of this formal framework is illustrated by reporting on some previous,and giving one new, example result(s) of computability and complexity incomputational physics.

physics.comp-ph cs.cc

10.1016/j.amc.2009.04.062

['ziegler']

https://arxiv.org/abs/0805.1292

grammatical evolution with restarts for fast fractal generation

0805.1696

in a previous work, the authors proposed a grammatical evolution algorithm toautomatically generate lindenmayer systems which represent fractal curves witha pre-determined fractal dimension. this paper gives strong statisticalevidence that the probability distributions of the execution time of thatalgorithm exhibits a heavy tail with an hyperbolic probability decay for longexecutions, which explains the erratic performance of different executions ofthe algorithm. three different restart strategies have been incorporated in thealgorithm to mitigate the problems associated to heavy tail distributions: thefirst assumes full knowledge of the execution time probability distribution,the second and third assume no knowledge. these strategies exploit the factthat the probability of finding a solution in short executions isnon-negligible and yield a severe reduction, both in the expected executiontime (up to one order of magnitude) and in its variance, which is reduced froman infinite to a finite value.

cs.ne cs.sc

nan

['cebrian', 'alfonseca', 'ortega']

https://arxiv.org/abs/0805.1696

certified exact transcendental real number computation in coq

0805.2438

reasoning about real number expressions in a proof assistant is challenging.several problems in theorem proving can be solved by using exact real numbercomputation. i have implemented a library for reasoning and computing withcomplete metric spaces in the coq proof assistant and used this library tobuild a constructive real number implementation including elementary realnumber functions and proofs of correctness. using this library, i have createda tactic that automatically proves strict inequalities over closed elementaryreal number expressions by computation.

cs.lo cs.ms cs.na

10.1007/978-3-540-71067-7_21

["o'connor"]

https://arxiv.org/abs/0805.2438

on the entropy and log-concavity of compound poisson measures

0805.4112

motivated, in part, by the desire to develop an information-theoreticfoundation for compound poisson approximation limit theorems (analogous to thecorresponding developments for the central limit theorem and for simple poissonapproximation), this work examines sufficient conditions under which thecompound poisson distribution has maximal entropy within a natural class ofprobability measures on the nonnegative integers. we show that the naturalanalog of the poisson maximum entropy property remains valid if the measuresunder consideration are log-concave, but that it fails in general. a parallelmaximum entropy result is established for the family of compound binomialmeasures. the proofs are largely based on ideas related to the semigroupapproach introduced in recent work by johnson for the poisson family.sufficient conditions are given for compound distributions to be log-concave,and specific examples are presented illustrating all the above results.

cs.it math.it math.pr

nan

['johnson', 'kontoyiannis', 'madiman']

https://arxiv.org/abs/0805.4112

subresultants in recursive polynomial remainder sequence

0806.0478

we introduce concepts of "recursive polynomial remainder sequence (prs)" and"recursive subresultant," and investigate their properties. in calculating prs,if there exists the gcd (greatest common divisor) of initial polynomials, wecalculate "recursively" with new prs for the gcd and its derivative, until aconstant is derived. we call such a prs a recursive prs. we define recursivesubresultants to be determinants representing the coefficients in recursive prsby coefficients of initial polynomials. finally, we discuss usage of recursivesubresultants in approximate algebraic computation, which motivates the presentwork.

math.ac cs.sc

nan

['terui']

https://arxiv.org/abs/0806.0478

recursive polynomial remainder sequence and the nested subresultants

0806.0488

we give two new expressions of subresultants, nested subresultant and reducednested subresultant, for the recursive polynomial remainder sequence (prs)which has been introduced by the author. the reduced nested subresultantreduces the size of the subresultant matrix drastically compared with therecursive subresultant proposed by the authors before, hence it is much moreuseful for investigation of the recursive prs. finally, we discuss usage of thereduced nested subresultant in approximate algebraic computation, whichmotivates the present work.

math.ac cs.sc

10.1007/11555964_38

['terui']

https://arxiv.org/abs/0806.0488

recursive polynomial remainder sequence and its subresultants

0806.0495

we introduce concepts of "recursive polynomial remainder sequence (prs)" and"recursive subresultant," along with investigation of their properties. arecursive prs is defined as, if there exists the gcd (greatest common divisor)of initial polynomials, a sequence of prss calculated "recursively" for the gcdand its derivative until a constant is derived, and recursive subresultants aredefined by determinants representing the coefficients in recursive prs asfunctions of coefficients of initial polynomials. we give three differentconstructions of subresultant matrices for recursive subresultants; while thefirst one is built-up just with previously defined matrices thus the size ofthe matrix increases fast as the recursion deepens, the last one reduces thesize of the matrix drastically by the gaussian elimination on the second onewhich has a "nested" expression, i.e. a sylvester matrix whose elements arethemselves determinants.

math.ac cs.sc

10.1016/j.jalgebra.2007.12.023

['terui']

https://arxiv.org/abs/0806.0495

drawing (complete) binary tanglegrams: hardness, approximation, fixed-parameter tractability

0806.0920

a \emph{binary tanglegram} is a drawing of a pair of rooted binary treeswhose leaf sets are in one-to-one correspondence; matching leaves are connectedby inter-tree edges. for applications, for example, in phylogenetics, it isessential that both trees are drawn without edge crossings and that theinter-tree edges have as few crossings as possible. it is known that finding atanglegram with the minimum number of crossings is np-hard and that the problemis fixed-parameter tractable with respect to that number. we prove that under the unique games conjecture there is no constant-factorapproximation for binary trees. we show that the problem is np-hard even ifboth trees are complete binary trees. for this case we give an $o(n^3)$-time2-approximation and a new, simple fixed-parameter algorithm. we show that themaximization version of the dual problem for binary trees can be reduced to aversion of maxcut for which the algorithm of goemans and williamson yields a0.878-approximation.

cs.cg cs.cc

nan

['buchin', 'buchin', 'byrka', 'nöllenburg', 'okamoto', 'silveira', 'wolff']

https://arxiv.org/abs/0806.0920

on convergence-sensitive bisimulation and the embedding of ccs in timed ccs

0806.0936

we propose a notion of convergence-sensitive bisimulation that is built justover the notions of (internal) reduction and of (static) context. in theframework of timed ccs, we characterise this notion of `contextual'bisimulation via the usual labelled transition system. we also remark that itprovides a suitable semantic framework for a fully abstract embedding ofuntimed processes into timed ones. finally, we show that the notion can berefined to include sensitivity to divergence.

cs.lo

nan

['amadio']

https://arxiv.org/abs/0806.0936

unsatisfiable cnf formulas need many conflicts

0806.1148

a pair of clauses in a cnf formula constitutes a conflict if there is avariable that occurs positively in one clause and negatively in the other. acnf formula without any conflicts is satisfiable. the lovasz local lemmaimplies that a k-cnf formula is satisfiable if each clause conflicts with atmost 2^k/e-1 clauses. it does not, however, give any good bound on how manyconflicts an unsatisfiable formula has globally. we show here that everyunsatisfiable k-cnf formula requires 2.69^k conflicts and there existunsatisfiable k-cnf formulas with 3.51^k conflicts.

cs.dm

nan

['scheder', 'zumstein']

https://arxiv.org/abs/0806.1148

performance of ldpc codes under faulty iterative decoding

0806.1215

departing from traditional communication theory where decoding algorithms areassumed to perform without error, a system where noise perturbs bothcomputational devices and communication channels is considered here. this paperstudies limits in processing noisy signals with noisy circuits by investigatingthe effect of noise on standard iterative decoders for low-density parity-checkcodes. concentration of decoding performance around its average is shown tohold when noise is introduced into message-passing and local computation.density evolution equations for simple faulty iterative decoders are derived.in one model, computing nonlinear estimation thresholds shows that performancedegrades smoothly as decoder noise increases, but arbitrarily small probabilityof error is not achievable. probability of error may be driven to zero inanother system model; the decoding threshold again decreases smoothly withdecoder noise. as an application of the methods developed, an achievabilityresult for reliable memory systems constructed from unreliable components isprovided.

cs.it math.it

nan

['varshney']

https://arxiv.org/abs/0806.1215

improving classical authentication with quantum communication

0806.1231

we propose a quantum-enhanced protocol to authenticate classical messages,with improved security with respect to the classical scheme introduced bybrassard in 1983. in that protocol, the shared key is the seed of apseudo-random generator (prg) and a hash function is used to create theauthentication tag of a public message. we show that a quantum encoding ofsecret bits offers more security than the classical xor function introduced bybrassard. furthermore, we establish the relationship between the bias of a prgand the amount of information about the key that the attacker can retrieve froma block of authenticated messages. finally, we prove that quantum resources canimprove both the secrecy of the key generated by the prg and the secrecy of thetag obtained with a hidden hash function.

cs.it cs.cr math.it

nan

['assis', 'mateus', 'omar']

https://arxiv.org/abs/0806.1231

a random search framework for convergence analysis of distributed beamforming with feedback

0806.3023

the focus of this work is on the analysis of transmit beamforming schemeswith a low-rate feedback link in wireless sensor/relay networks, where nodes inthe network need to implement beamforming in a distributed manner.specifically, the problem of distributed phase alignment is considered, whereneither the transmitters nor the receiver has perfect channel stateinformation, but there is a low-rate feedback link from the receiver to thetransmitters. in this setting, a framework is proposed for systematicallyanalyzing the performance of distributed beamforming schemes. to illustrate theadvantage of this framework, a simple adaptive distributed beamforming schemethat was recently proposed by mudambai et al. is studied. two importantproperties for the received signal magnitude function are derived. using theseproperties and the systematic framework, it is shown that the adaptivedistributed beamforming scheme converges both in probability and in mean.furthermore, it is established that the time required for the adaptive schemeto converge in mean scales linearly with respect to the number of sensor/relaynodes.

cs.dc cs.it math.it

nan

['lin', 'veeravalli', 'meyn']

https://arxiv.org/abs/0806.3023

a computer verified theory of compact sets

0806.3209

compact sets in constructive mathematics capture our intuition of whatcomputable subsets of the plane (or any other complete metric space) ought tobe. a good representation of compact sets provides an efficient means ofcreating and displaying images with a computer. in this paper, i build uponexisting work about complete metric spaces to define compact sets as thecompletion of the space of finite sets under the hausdorff metric. thisdefinition allowed me to quickly develop a computer verified theory of compactsets. i applied this theory to compute provably correct plots of uniformlycontinuous functions.

cs.lo

nan

["o'connor"]

https://arxiv.org/abs/0806.3209

stabilizing tiny interaction protocols

0806.3471

in this paper we present the self-stabilizing implementation of a class oftoken based algorithms. in the current work we only consider interactionsbetween weak nodes. they are uniform, they do not have unique identifiers, arestatic and their interactions are restricted to a subset of nodes calledneighbours. while interacting, a pair of neighbouring nodes may create mobileagents (that materialize in the current work the token abstraction) thatperform traversals of the network and accelerate the system stabilization. inthis work we only explore the power of oblivious stateless agents. our work shows that the agent paradigm is an elegant distributed tool forachieving self-stabilization in tiny interaction protocols (tip). nevertheless,in order to reach the full power of classical self-stabilizing algorithms morecomplex classes of agents have to be considered (e.g. agents with memory,identifiers or communication skills). interestingly, our work proposes for thefirst time a model that unifies the recent studies in mobile robots(agents)that evolve in a discrete space and the already established populationprotocols paradigm.

cs.dc cs.ds

nan

['canepa', 'potop-butucaru']

https://arxiv.org/abs/0806.3471

"minesweeper" and spectrum of discrete laplacians

0806.3480

the paper is devoted to a problem inspired by the "minesweeper" computergame. it is shown that certain configurations of open cells guarantee theexistence and the uniqueness of solution. mathematically the problem is reducedto some spectral properties of discrete differential operators. it is shown howthe uniqueness can be used to create a new game which preserves the spirit of"minesweeper" but does not require a computer.

cs.dm

10.1080/00036811.2010.505189

['german', 'lakshtanov']

https://arxiv.org/abs/0806.3480

computational approaches to measuring the similarity of short contexts : a review of applications and methods

0806.3787

measuring the similarity of short written contexts is a fundamental problemin natural language processing. this article provides a unifying framework bywhich short context problems can be categorized both by their intendedapplication and proposed solution. the goal is to show that various problemsand methodologies that appear quite different on the surface are in fact veryclosely related. the axes by which these categorizations are made include theformat of the contexts (headed versus headless), the way in which the contextsare to be measured (first-order versus second-order similarity), and theinformation used to represent the features in the contexts (micro versus macroviews). the unifying thread that binds together many short context applicationsand methods is the fact that similarity decisions must be made between contextsthat share few (if any) words in common.

cs.cl

nan

['pedersen']

https://arxiv.org/abs/0806.3787

the heap lambda machine

0806.4631

this paper introduces a new machine architecture for evaluating lambdaexpressions using the normal-order reduction, which guarantees that everylambda expression will be evaluated if the expression has its normal form andthe system has enough memory. the architecture considered here operates usingheap memory only. lambda expressions are represented as graphs, and allalgorithms used in the processing unit of this machine are non-recursive.

cs.lo

nan

['salikhmetov']

https://arxiv.org/abs/0806.4631

concept-oriented programming

0806.4746

object-oriented programming (oop) is aimed at describing the structure andbehaviour of objects by hiding the mechanism of their representation and accessin primitive references. in this article we describe an approach, calledconcept-oriented programming (cop), which focuses on modelling referencesassuming that they also possess application-specific structure and behaviouraccounting for a great deal or even most of the overall program complexity.references in cop are completely legalized and get the same status as objectswhile the functions are distributed among both objects and references. in orderto support this design we introduce a new programming construct, calledconcept, which generalizes conventional classes and concept inclusion relationgeneralizing class inheritance. the main advantage of cop is that it allowsprogrammers to describe two sides of any program: explicitly used functions ofobjects and intermediate functionality of references having cross-cuttingnature and executed implicitly behind the scenes during object access.

cs.pl

nan

['savinov']

https://arxiv.org/abs/0806.4746

ams without 4-wise independence on product domains

0806.4790

in their seminal work, alon, matias, and szegedy introduced several sketchingtechniques, including showing that 4-wise independence is sufficient to obtaingood approximations of the second frequency moment. in this work, we show thattheir sketching technique can be extended to product domains $[n]^k$ by usingthe product of 4-wise independent functions on $[n]$. our work extends that ofindyk and mcgregor, who showed the result for $k = 2$. their primary motivationwas the problem of identifying correlations in data streams. in their model, astream of pairs $(i,j) \in [n]^2$ arrive, giving a joint distribution $(x,y)$,and they find approximation algorithms for how close the joint distribution isto the product of the marginal distributions under various metrics, whichnaturally corresponds to how close $x$ and $y$ are to being independent. byusing our technique, we obtain a new result for the problem of approximatingthe $\ell_2$ distance between the joint distribution and the product of themarginal distributions for $k$-ary vectors, instead of just pairs, in a singlepass. our analysis gives a randomized algorithm that is a $(1 \pm \epsilon)$approximation (with probability $1-\delta$) that requires space logarithmic in$n$ and $m$ and proportional to $3^k$.

cs.ds

nan

['braverman', 'chung', 'liu', 'mitzenmacher', 'ostrovsky']

https://arxiv.org/abs/0806.4790

myopic coding in multiterminal networks

0806.4874

this paper investigates the interplay between cooperation and achievablerates in multi-terminal networks. cooperation refers to the process of nodesworking together to relay data toward the destination. there is an inherenttradeoff between achievable information transmission rates and the level ofcooperation, which is determined by how many nodes are involved and how thenodes encode/decode the data. we illustrate this trade-off by studyinginformation-theoretic decode-forward based coding strategies for datatransmission in multi-terminal networks. decode-forward strategies are usuallydiscussed in the context of omniscient coding, in which all nodes in thenetwork fully cooperate with each other, both in encoding and decoding. in thispaper, we investigate myopic coding, in which each node cooperates with only afew neighboring nodes. we show that achievable rates of myopic decode-forwardcan be as large as that of omniscient decode-forward in the low snr regime. wealso show that when each node has only a few cooperating neighbors, adding onenode into the cooperation increases the transmission rate significantly.furthermore, we show that myopic decode-forward can achieve non-zero rates asthe network size grows without bound.

cs.it math.it

10.1109/tit.2008.924675

['ong', 'motani']

https://arxiv.org/abs/0806.4874

a novel mathematical model for the unique shortest path routing problem

0807.0038

link weights are the principal parameters of shortest path routing protocols,the most commonly used protocols for ip networks. the problem of optimallysetting link weights for unique shortest path routing is addressed. due to thecomplexity of the constraints involved, there exist challenges to formulate theproblem properly, so that a solution algorithm may be developed which couldprove to be more efficient than those already in existence. in this paper, anovel complete formulation with a polynomial number of constraints is firstintroduced and then mathematically proved to be correct. it is furtherillustrated that the formulation has advantages over a prior one in terms ofboth constraint structure and model size for a proposed decomposition method tosolve the problem.

math.oc cs.ds

nan

['zhang']

https://arxiv.org/abs/0807.0038

graph kernels

0807.0093

we present a unified framework to study graph kernels, special cases of whichinclude the random walk graph kernel \citep{gaeflawro03,borongschvisetal05},marginalized graph kernel \citep{kastsuino03,kastsuino04,mahuedakuperetal04},and geometric kernel on graphs \citep{gaertner02}. through extensions of linearalgebra to reproducing kernel hilbert spaces (rkhs) and reduction to asylvester equation, we construct an algorithm that improves the time complexityof kernel computation from $o(n^6)$ to $o(n^3)$. when the graphs are sparse,conjugate gradient solvers or fixed-point iterations bring our algorithm intothe sub-cubic domain. experiments on graphs from bioinformatics and otherapplication domains show that it is often more than a thousand times fasterthan previous approaches. we then explore connections between diffusion kernels\citep{konlaf02}, regularization on graphs \citep{smokon03}, and graph kernels,and use these connections to propose new graph kernels. finally, we show thatrational kernels \citep{corhafmoh02,corhafmoh03,corhafmoh04} when specializedto graphs reduce to the random walk graph kernel.

cs.lg

nan

['vishwanathan', 'borgwardt', 'kondor', 'schraudolph']

https://arxiv.org/abs/0807.0093

virtual transmission method, a new distributed algorithm to solve sparse linear system

0807.1949

in this paper, we propose a new parallel algorithm which could work naturallyon the parallel computer with arbitrary number of processors. this algorithm isnamed virtual transmission method (vtm). its physical backgroud is the losslesstransmission line and microwave network. the basic idea of vtm is to insertlossless transmission lines into the sparse linear system to achievedistributed computing. vtm is proved to be convergent to solve spd linear system. preconditioningmethod and performance model are presented. numerical experiments show that vtmis efficient, accurate and stable. accompanied with vtm, we bring in a new technique to partition the symmetriclinear system, which is named generalized node & branch tearing (gnbt). it isbased on kirchhoff's current law from circuit theory. we proved that gnbt isfeasible to partition any spd linear system.

math.na cs.dc

10.1109/ncm.2008.160

['wei', 'yang']

https://arxiv.org/abs/0807.1949

a new characteristic property of rich words

0807.2303

originally introduced and studied by the third and fourth authors togetherwith j. justin and s. widmer in arxiv:0801.1656, rich words constitute a newclass of finite and infinite words characterized by containing the maximalnumber of distinct palindromes. several characterizations of rich words havealready been established. a particularly nice characteristic property is thatall 'complete returns' to palindromes are palindromes. in this note, we provethat rich words are also characterized by the property that each factor isuniquely determined by its longest palindromic prefix and its longestpalindromic suffix.

math.co cs.dm

10.1016/j.tcs.2008.11.001

['bucci', 'de luca', 'glen', 'zamboni']

https://arxiv.org/abs/0807.2303

polygon exploration with time-discrete vision

0807.2358

with the advent of autonomous robots with two- and three-dimensional scanningcapabilities, classical visibility-based exploration methods from computationalgeometry have gained in practical importance. however, real-life laser scanningof useful accuracy does not allow the robot to scan continuously while inmotion; instead, it has to stop each time it surveys its environment. thisrequirement was studied by fekete, klein and nuechter for the subproblem oflooking around a corner, but until now has not been considered in an onlinesetting for whole polygonal regions. we give the first algorithmic results for this important algorithmic problemthat combines stationary art gallery-type aspects with watchman-type issues inan online scenario: we demonstrate that even for orthoconvex polygons, acompetitive strategy can be achieved only for limited aspect ratio a (the ratioof the maximum and minimum edge length of the polygon), i.e., for a given lowerbound on the size of an edge; we give a matching upper bound by providing ano(log a)-competitive strategy for simple rectilinear polygons, using theassumption that each edge of the polygon has to be fully visible from some scanpoint.

cs.cg cs.ro

nan

['fekete', 'schmidt']

https://arxiv.org/abs/0807.2358

algorithms for dynamic spectrum access with learning for cognitive radio

0807.2677

we study the problem of dynamic spectrum sensing and access in cognitiveradio systems as a partially observed markov decision process (pomdp). a groupof cognitive users cooperatively tries to exploit vacancies in primary(licensed) channels whose occupancies follow a markovian evolution. we firstconsider the scenario where the cognitive users have perfect knowledge of thedistribution of the signals they receive from the primary users. for thisproblem, we obtain a greedy channel selection and access policy that maximizesthe instantaneous reward, while satisfying a constraint on the probability ofinterfering with licensed transmissions. we also derive an analytical universalupper bound on the performance of the optimal policy. through simulation, weshow that our scheme achieves good performance relative to the upper bound andimproved performance relative to an existing scheme. we then consider the more practical scenario where the exact distribution ofthe signal from the primary is unknown. we assume a parametric model for thedistribution and develop an algorithm that can learn the true distribution,still guaranteeing the constraint on the interference probability. we show thatthis algorithm outperforms the naive design that assumes a worst case value forthe parameter. we also provide a proof for the convergence of the learningalgorithm.

cs.ni cs.lg

nan

['unnikrishnan', 'veeravalli']

https://arxiv.org/abs/0807.2677

the transport capacity of a wireless network is a subadditive euclidean functional

0807.2859

the transport capacity of a dense ad hoc network with n nodes scales like\sqrt(n). we show that the transport capacity divided by \sqrt(n) approaches anon-random limit with probability one when the nodes are i.i.d. distributed onthe unit square. we prove that the transport capacity under the protocol modelis a subadditive euclidean functional and use the machinery of subadditivefunctions in the spirit of steele to show the existence of the limit.

cs.it math.it

10.1239/jap/1285335416

['ganti', 'haenggi']

https://arxiv.org/abs/0807.2859

an image processing analysis of skin textures

0807.4701

colour and coarseness of skin are visually different. when image processingis involved in the skin analysis, it is important to quantitatively evaluatesuch differences using texture features. in this paper, we discuss a textureanalysis and measurements based on a statistical approach to the patternrecognition. grain size and anisotropy are evaluated with proper diagrams. thepossibility to determine the presence of pattern defects is also discussed.

cs.cv

10.1111/j.1600-0846.2009.00413.x

['sparavigna', 'marazzato']

https://arxiv.org/abs/0807.4701

stay by thy neighbor? social organization determines the efficiency of biodiversity markets with spatial incentives

0808.0111

market-based conservation instruments, such as payments, auctions or tradablepermits, are environmental policies that create financial incentives forlandowners to engage in voluntary conservation on their land. but what ifecological processes operate across property boundaries and land use decisionson one property influence ecosystem functions on neighboring sites? this paperexamines how to account for such spatial externalities when designingmarket-based conservation instruments. we use an agent-based model to analyzedifferent spatial metrics and their implications on land use decisions in adynamic cost environment. the model contains a number of alternative submodelswhich differ in incentive design and social interactions of agents, the latterincluding coordinating as well as cooperating behavior of agents. we find thatincentive design and social interactions have a strong influence on the spatialallocation and the costs of the conservation market.

physics.soc-ph cs.gt

10.1016/j.ecocom.2009.07.001

['hartig', 'drechsler']

https://arxiv.org/abs/0808.0111

mathematical structure of quantum decision theory

0808.0112

one of the most complex systems is the human brain whose formalizedfunctioning is characterized by decision theory. we present a "quantum decisiontheory" of decision making, based on the mathematical theory of separablehilbert spaces. this mathematical structure captures the effect ofsuperposition of composite prospects, including many incorporated intentions,which allows us to explain a variety of interesting fallacies and anomaliesthat have been reported to particularize the decision making of real humanbeings. the theory describes entangled decision making, non-commutativity ofsubsequent decisions, and intention interference of composite prospects. wedemonstrate how the violation of the savage's sure-thing principle (disjunctioneffect) can be explained as a result of the interference of intentions, whenmaking decisions under uncertainty. the conjunction fallacy is also explainedby the presence of the interference terms. we demonstrate that all knownanomalies and paradoxes, documented in the context of classical decisiontheory, are reducible to just a few mathematical archetypes, all of whichfinding straightforward explanations in the frame of the developed quantumapproach.

cs.ai math-ph math.mp quant-ph

nan

['yukalov', 'sornette']

https://arxiv.org/abs/0808.0112

uniqueness of certain polynomials constant on a line

0808.0284

we study a question with connections to linear algebra, real algebraicgeometry, combinatorics, and complex analysis. let $p(x,y)$ be a polynomial ofdegree $d$ with $n$ positive coefficients and no negative coefficients, suchthat $p=1$ when $x+y=1$. a sharp estimate $d \leq 2n-3$ is known. in this paperwe study the $p$ for which equality holds. we prove some new results about theform of these "sharp" polynomials. using these new results and using twoindependent computational methods we give a complete classification of thesepolynomials up to $d=17$. the question is motivated by the problem ofclassification of cr maps between spheres in different dimensions.

math.cv cs.cg math.nt

10.1016/j.laa.2010.04.020

['lebl', 'lichtblau']

https://arxiv.org/abs/0808.0284

computing the nucleolus of weighted voting games

0808.0298

weighted voting games (wvg) are coalitional games in which an agent'scontribution to a coalition is given by his it weight, and a coalition wins ifits total weight meets or exceeds a given quota. these games modeldecision-making in political bodies as well as collaboration and surplusdivision in multiagent domains. the computational complexity of varioussolution concepts for weighted voting games received a lot of attention inrecent years. in particular, elkind et al.(2007) studied the complexity ofstability-related solution concepts in wvgs, namely, of the core, the leastcore, and the nucleolus. while they have completely characterized thealgorithmic complexity of the core and the least core, for the nucleolus theyhave only provided an np-hardness result. in this paper, we solve an openproblem posed by elkind et al. by showing that the nucleolus of wvgs, and, moregenerally, k-vector weighted voting games with fixed k, can be computed inpseudopolynomial time, i.e., there exists an algorithm that correctly computesthe nucleolus and runs in time polynomial in the number of players and themaximum weight. in doing so, we propose a general framework for computing thenucleolus, which may be applicable to a wider of class of games.

cs.gt cs.ds

10.1145/1496770.1496807

['elkind', 'pasechnik']

https://arxiv.org/abs/0808.0298

evolving clustered random networks

0808.0509

we propose a markov chain simulation method to generate simple connectedrandom graphs with a specified degree sequence and level of clustering. thenetworks generated by our algorithm are random in all other respects and canthus serve as generic models for studying the impacts of degree distributionsand clustering on dynamical processes as well as null models for detectingother structural properties in empirical networks.

cs.dm physics.soc-ph

10.1186/1471-2105-10-405

['bansal', 'khandelwal', 'meyers']

https://arxiv.org/abs/0808.0509

the peculiar phase structure of random graph bisection

0808.1549

the mincut graph bisection problem involves partitioning the n vertices of agraph into disjoint subsets, each containing exactly n/2 vertices, whileminimizing the number of "cut" edges with an endpoint in each subset. whenconsidered over sparse random graphs, the phase structure of the graphbisection problem displays certain familiar properties, but also somesurprises. it is known that when the mean degree is below the critical value of2 log 2, the cutsize is zero with high probability. we study how the minimumcutsize increases with mean degree above this critical threshold, finding a newanalytical upper bound that improves considerably upon previous bounds.combined with recent results on expander graphs, our bound suggests the unusualscenario that random graph bisection is replica symmetric up to and beyond thecritical threshold, with a replica symmetry breaking transition possibly takingplace above the threshold. an intriguing algorithmic consequence is thatalthough the problem is np-hard, we can find near-optimal cutsizes (whose ratioto the optimal value approaches 1 asymptotically) in polynomial time fortypical instances near the phase transition.

cond-mat.stat-mech cond-mat.dis-nn cs.cc cs.dm

10.1063/1.3043666

['percus', 'istrate', 'goncalves', 'sumi', 'boettcher']

https://arxiv.org/abs/0808.1549

solving the apparent diversity-accuracy dilemma of recommender systems

0808.2670

recommender systems use data on past user preferences to predict possiblefuture likes and interests. a key challenge is that while the most usefulindividual recommendations are to be found among diverse niche objects, themost reliably accurate results are obtained by methods that recommend objectsbased on user or object similarity. in this paper we introduce a new algorithmspecifically to address the challenge of diversity and show how it can be usedto resolve this apparent dilemma when combined in an elegant hybrid with anaccuracy-focused algorithm. by tuning the hybrid appropriately we are able toobtain, without relying on any semantic or context-specific information,simultaneous gains in both accuracy and diversity of recommendations.

cs.ir physics.soc-ph

10.1073/pnas.1000488107

['zhou', 'kuscsik', 'liu', 'medo', 'wakeling', 'zhang']

https://arxiv.org/abs/0808.2670

n-ary fuzzy logic and neutrosophic logic operators

0808.3109

we extend knuth's 16 boolean binary logic operators to fuzzy logic andneutrosophic logic binary operators. then we generalize them to n-ary fuzzylogic and neutrosophic logic operators using the smarandache codification ofthe venn diagram and a defined vector neutrosophic law. in such way, newoperators in neutrosophic logic/set/probability are built.

cs.ai

nan

['smarandache', 'christianto']

https://arxiv.org/abs/0808.3109

the complexity of reasoning for fragments of default logic

0808.3884

default logic was introduced by reiter in 1980. in 1992, gottlob classifiedthe complexity of the extension existence problem for propositional defaultlogic as $\sigmaptwo$-complete, and the complexity of the credulous andskeptical reasoning problem as sigmap2-complete, resp. pip2-complete.additionally, he investigated restrictions on the default rules, i.e.,semi-normal default rules. selman made in 1992 a similar approach withdisjunction-free and unary default rules. in this paper we systematicallyrestrict the set of allowed propositional connectives. we give a completecomplexity classification for all sets of boolean functions in the meaning ofpost's lattice for all three common decision problems for propositional defaultlogic. we show that the complexity is a hexachotomy (sigmap2-, deltap2-, np-,p-, nl-complete, trivial) for the extension existence problem, while for thecredulous and skeptical reasoning problem we obtain similar classificationswithout trivial cases.

cs.cc cs.lo

nan

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

https://arxiv.org/abs/0808.3884

spectral sparsification of graphs

0808.4134

we introduce a new notion of graph sparsificaiton based on spectralsimilarity of graph laplacians: spectral sparsification requires that thelaplacian quadratic form of the sparsifier approximate that of the original.this is equivalent to saying that the laplacian of the sparsifier is a goodpreconditioner for the laplacian of the original. we prove that every graph hasa spectral sparsifier of nearly linear size. moreover, we present an algorithmthat produces spectral sparsifiers in time $\softo{m}$, where $m$ is the numberof edges in the original graph. this construction is a key component of anearly-linear time algorithm for solving linear equations indiagonally-dominant matrcies. our sparsification algorithm makes use of anearly-linear time algorithm for graph partitioning that satisfies a strongguarantee: if the partition it outputs is very unbalanced, then the larger partis contained in a subgraph of high conductance.

cs.ds cs.dm

nan

['spielman', 'teng']

https://arxiv.org/abs/0808.4134

instruction sequences and non-uniform complexity theory

0809.0352

we develop theory concerning non-uniform complexity in a setting in which thenotion of single-pass instruction sequence considered in program algebra is thecentral notion. we define counterparts of the complexity classes p/poly andnp/poly and formulate a counterpart of the complexity theoretic conjecture thatnp is not included in p/poly. in addition, we define a notion of completenessfor the counterpart of np/poly using a non-uniform reducibility relation andformulate complexity hypotheses which concern restrictions on the instructionsequences used for computation. we think that the theory developed opens up anadditional way of investigating issues concerning non-uniform complexity.

cs.cc

nan

['bergstra', 'middelburg']

https://arxiv.org/abs/0809.0352

approximating the volume of unions and intersections of high-dimensional geometric objects

0809.0835

we consider the computation of the volume of the union of high-dimensionalgeometric objects. while showing that this problem is #p-hard already for verysimple bodies (i.e., axis-parallel boxes), we give a fast fpras for all objectswhere one can: (1) test whether a given point lies inside the object, (2)sample a point uniformly, (3) calculate the volume of the object in polynomialtime. all three oracles can be weak, that is, just approximate. this impliesthat klee's measure problem and the hypervolume indicator can be approximatedefficiently even though they are #p-hard and hence cannot be solved exactly intime polynomial in the number of dimensions unless p=np. our algorithm alsoallows to approximate efficiently the volume of the union of convex bodiesgiven by weak membership oracles. for the analogous problem of the intersection of high-dimensional geometricobjects we prove #p-hardness for boxes and show that there is no multiplicativepolynomial-time $2^{d^{1-\epsilon}}$-approximation for certain boxes unlessnp=bpp, but give a simple additive polynomial-time $\epsilon$-approximation.

cs.cg cs.ne

10.1016/j.comgeo.2010.03.004

['bringmann', 'friedrich']

https://arxiv.org/abs/0809.0835

the golden ratio encoder

0809.1257

this paper proposes a novel nyquist-rate analog-to-digital (a/d) conversionalgorithm which achieves exponential accuracy in the bit-rate despite usingimperfect components. the proposed algorithm is based on a robustimplementation of a beta-encoder where the value of the base beta is equal togolden mean. it was previously shown that beta-encoders can be implemented insuch a way that their exponential accuracy is robust against threshold offsetsin the quantizer element. this paper extends this result by allowing forimperfect analog multipliers with imprecise gain values as well. a formalcomputational model for algorithmic encoders and a general test bed forevaluating their robustness is also proposed.

cs.it math.it

10.1109/tit.2010.2059750

['daubechies', 'güntürk', 'wang', 'yilmaz']

https://arxiv.org/abs/0809.1257

stability of maximum likelihood based clustering methods: exploring the backbone of classifications (who is keeping you in that community?)

0809.1398

components of complex systems are often classified according to the way theyinteract with each other. in graph theory such groups are known as clusters orcommunities. many different techniques have been recently proposed to detectthem, some of which involve inference methods using either bayesian or maximumlikelihood approaches. in this article, we study a statistical model designedfor detecting clusters based on connection similarity. the basic assumption ofthe model is that the graph was generated by a certain grouping of the nodesand an expectation maximization algorithm is employed to infer that grouping.we show that the method admits further development to yield a stabilityanalysis of the groupings that quantifies the extent to which each nodeinfluences its neighbors group membership. our approach naturally allows forthe identification of the key elements responsible for the grouping and theirresilience to changes in the network. given the generality of the assumptionsunderlying the statistical model, such nodes are likely to play special rolesin the original system. we illustrate this point by analyzing several empiricalnetworks for which further information about the properties of the nodes isavailable. the search and identification of stabilizing nodes constitutes thusa novel technique to characterize the relevance of nodes in complex networks.

physics.soc-ph cond-mat.stat-mech cs.it math.it physics.comp-ph physics.data-an

nan

['mungan', 'ramasco']

https://arxiv.org/abs/0809.1398

computing with classical real numbers

0809.1644

there are two incompatible coq libraries that have a theory of the realnumbers; the coq standard library gives an axiomatic treatment of classicalreal numbers, while the corn library from nijmegen defines constructively validreal numbers. unfortunately, this means results about one structure cannoteasily be used in the other structure. we present a way interfacing these twolibraries by showing that their real number structures are isomorphic assumingthe classical axioms already present in the standard library reals. this allowsus to use o'connor's decision procedure for solving ground inequalities presentin corn to solve inequalities about the reals from the coq standard library,and it allows theorems from the coq standard library to apply to problem aboutthe corn reals.

cs.lo

nan

['kaliszyk', "o'connor"]

https://arxiv.org/abs/0809.1644

multirate anypath routing in wireless mesh networks

0809.1681

in this paper, we present a new routing paradigm that generalizesopportunistic routing in wireless mesh networks. in multirate anypath routing,each node uses both a set of next hops and a selected transmission rate toreach a destination. using this rate, a packet is broadcast to the nodes in theset and one of them forwards the packet on to the destination. to date, thereis no theory capable of jointly optimizing both the set of next hops and thetransmission rate used by each node. we bridge this gap by introducing apolynomial-time algorithm to this problem and provide the proof of itsoptimality. the proposed algorithm runs in the same running time as regularshortest-path algorithms and is therefore suitable for deployment in link-staterouting protocols. we conducted experiments in a 802.11b testbed network, andour results show that multirate anypath routing performs on average 80% and upto 6.4 times better than anypath routing with a fixed rate of 11 mbps. if therate is fixed at 1 mbps instead, performance improves by up to one order ofmagnitude.

cs.ni cs.ds

10.1109/infcom.2009.5061904

['laufer', 'kleinrock']

https://arxiv.org/abs/0809.1681

fairness in combinatorial auctioning systems

0809.2168

one of the multi-agent systems that is widely used by various governmentagencies, buyers and sellers in a market economy, in such a manner so as toattain optimized resource allocation, is the combinatorial auctioning system(cas). we study another important aspect of resource allocations in cas, namelyfairness. we present two important notions of fairness in cas, extendedfairness and basic fairness. we give an algorithm that works by incorporating ametric to ensure fairness in a cas that uses the vickrey-clark-groves (vcg)mechanism, and uses an algorithm of sandholm to achieve optimality.mathematical formulations are given to represent measures of extended fairnessand basic fairness.

cs.gt cs.ma

nan

['saini', 'rao']

https://arxiv.org/abs/0809.2168

largest empty circle centered on a query line

0809.2651

the largest empty circle problem seeks the largest circle centered within theconvex hull of a set $p$ of $n$ points in $\mathbb{r}^2$ and devoid of pointsfrom $p$. in this paper, we introduce a query version of this well-studiedproblem. in our query version, we are required to preprocess $p$ so that whengiven a query line $q$, we can quickly compute the largest empty circlecentered at some point on $q$ and within the convex hull of $p$. we present solutions for two special cases and the general case; all ourqueries run in $o(\log n)$ time. we restrict the query line to be horizontal inthe first special case, which we preprocess in $o(n \alpha(n) \log n)$ time andspace, where $\alpha(n)$ is the slow growing inverse of the ackermann'sfunction. when the query line is restricted to pass through a fixed point, thesecond special case, our preprocessing takes $o(n \alpha(n)^{o(\alpha(n))} \logn)$ time and space. we use insights from the two special cases to solve thegeneral version of the problem with preprocessing time and space in $o(n^3 \logn)$ and $o(n^3)$ respectively.

cs.cg

10.1016/j.jda.2009.10.002

['augustine', 'putnam', 'roy']

https://arxiv.org/abs/0809.2651

extended asp tableaux and rule redundancy in normal logic programs

0809.3204

we introduce an extended tableau calculus for answer set programming (asp).the proof system is based on the asp tableaux defined in [gebser&schaub, iclp2006], with an added extension rule. we investigate the power of extended asptableaux both theoretically and empirically. we study the relationship ofextended asp tableaux with the extended resolution proof system defined bytseitin for sets of clauses, and separate extended asp tableaux from asptableaux by giving a polynomial-length proof for a family of normal logicprograms p_n for which asp tableaux has exponential-length minimal proofs withrespect to n. additionally, extended asp tableaux imply interesting insightinto the effect of program simplification on the lengths of proofs in asp.closely related to extended asp tableaux, we empirically investigate the effectof redundant rules on the efficiency of asp solving. to appear in theory and practice of logic programming (tplp).

cs.ai

10.1017/s1471068408003578

['järvisalo', 'oikarinen']

https://arxiv.org/abs/0809.3204

fermions and loops on graphs. i. loop calculus for determinant

0809.3479

this paper is the first in the series devoted to evaluation of the partitionfunction in statistical models on graphs with loops in terms of theberezin/fermion integrals. the paper focuses on a representation of thedeterminant of a square matrix in terms of a finite series, where each termcorresponds to a loop on the graph. the representation is based on a fermionversion of the loop calculus, previously introduced by the authors forgraphical models with finite alphabets. our construction contains two levels.first, we represent the determinant in terms of an integral over anti-commutinggrassman variables, with some reparametrization/gauge freedom hidden in theformulation. second, we show that a special choice of the gauge, called bp(bethe-peierls or belief propagation) gauge, yields the desired looprepresentation. the set of gauge-fixing bp conditions is equivalent to thegaussian bp equations, discussed in the past as efficient (linear scaling)heuristics for estimating the covariance of a sparse positive matrix.

cond-mat.stat-mech cond-mat.dis-nn cs.cc cs.it hep-th math.it

10.1088/1742-5468/2008/12/p12011

['chernyak', 'chertkov']

https://arxiv.org/abs/0809.3479

fermions and loops on graphs. ii. monomer-dimer model as series of determinants

0809.3481

we continue the discussion of the fermion models on graphs that started inthe first paper of the series. here we introduce a graphical gauge model (ggm)and show that : (a) it can be stated as an average/sum of a determinant definedon the graph over $\mathbb{z}_{2}$ (binary) gauge field; (b) it is equivalentto the monomer-dimer (md) model on the graph; (c) the partition function of themodel allows an explicit expression in terms of a series over disjoint directedcycles, where each term is a product of local contributions along the cycle andthe determinant of a matrix defined on the remainder of the graph (excludingthe cycle). we also establish a relation between the md model on the graph andthe determinant series, discussed in the first paper, however, considered usingsimple non-belief-propagation choice of the gauge. we conclude with adiscussion of possible analytic and algorithmic consequences of these results,as well as related questions and challenges.

cond-mat.stat-mech cond-mat.dis-nn cs.cc cs.it hep-th math.it

10.1088/1742-5468/2008/12/p12012

['chernyak', 'chertkov']

https://arxiv.org/abs/0809.3481

dynamic tree algorithms

0809.3577

in this paper, a general tree algorithm processing a random flow of arrivalsis analyzed. capetanakis--tsybakov--mikhailov's protocol in the context ofcommunication networks with random access is an example of such an algorithm.in computer science, this corresponds to a trie structure with a dynamic input.mathematically, it is related to a stopped branching process with exogeneousarrivals (immigration). under quite general assumptions on the distribution ofthe number of arrivals and on the branching procedure, it is shown that thereexists a positive constant $\lambda_c$ so that if the arrival rate is smallerthan $\lambda_c$, then the algorithm is stable under the flow of requests, thatis, that the total size of an associated tree is integrable. at the same time,a gap in the earlier proofs of stability in the literature is fixed. when thearrivals are poisson, an explicit characterization of $\lambda_c$ is given.under the stability condition, the asymptotic behavior of the average size of atree starting with a large number of individuals is analyzed. the results areobtained with the help of a probabilistic rewriting of the functional equationsdescribing the dynamics of the system. the proofs use extensively thisstochastic background throughout the paper. in this analysis, two basic limittheorems play a key role: the renewal theorem and the convergence toequilibrium of an auto-regressive process with a moving average.

math.pr cs.ds

10.1214/09-aap617

['mohamed', 'robert']

https://arxiv.org/abs/0809.3577