Results for "Thomas Prescher"

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LazyFP: Leaking FPU Register State using Microarchitectural Side-ChannelsJun 19 2018Modern processors utilize an increasingly large register set to facilitate efficient floating point and SIMD computation. This large register set is a burden for operating systems, as its content needs to be saved and restored when the operating system ... More
A Tutorial on the Expectation-Maximization Algorithm Including Maximum-Likelihood Estimation and EM Training of Probabilistic Context-Free GrammarsDec 03 2004Mar 11 2005The paper gives a brief review of the expectation-maximization algorithm (Dempster 1977) in the comprehensible framework of discrete mathematics. In Section 2, two prominent estimation methods, the relative-frequency estimation and the maximum-likelihood ... More
Inside-Outside Estimation Meets Dynamic EMDec 03 2004We briefly review the inside-outside and EM algorithm for probabilistic context-free grammars. As a result, we formally prove that inside-outside estimation is a dynamic-programming variant of EM. This is interesting in its own right, but even more when ... More
ZombieLoad: Cross-Privilege-Boundary Data SamplingMay 14 2019In early 2018, Meltdown first showed how to read arbitrary kernel memory from user space by exploiting side-effects from transient instructions. While this attack has been mitigated through stronger isolation boundaries between user and kernel space, ... More
Spectre Attacks: Exploiting Speculative ExecutionJan 03 2018Modern processors use branch prediction and speculative execution to maximize performance. For example, if the destination of a branch depends on a memory value that is in the process of being read, CPUs will try guess the destination and attempt to execute ... More
MeltdownJan 03 2018The security of computer systems fundamentally relies on memory isolation, e.g., kernel address ranges are marked as non-accessible and are protected from user access. In this paper, we present Meltdown. Meltdown exploits side effects of out-of-order ... More
Long-Term Radio Modulation in Sagittarius A* from Spin-Induced Disk PrecessionMay 17 2005Jun 25 2005There is some evidence, though yet unconfirmed, that Sagittarius A*--the supermassive black hole at the Galactic center--emits its radio waves modulated with a ~100-day period. What is intriguing about this apparent quasi-periodicity is that, though the ... More
Using a Probabilistic Class-Based Lexicon for Lexical Ambiguity ResolutionAug 30 2000This paper presents the use of probabilistic class-based lexica for disambiguation in target-word selection. Our method employs minimal but precise contextual information for disambiguation. That is, only information provided by the target-verb, enriched ... More
Inducing a Semantically Annotated Lexicon via EM-Based ClusteringMay 19 1999We present a technique for automatic induction of slot annotations for subcategorization frames, based on induction of hidden classes in the EM framework of statistical estimation. The models are empirically evalutated by a general decision test. Induction ... More
Inside-Outside Estimation of a Lexicalized PCFG for GermanMay 19 1999The paper describes an extensive experiment in inside-outside estimation of a lexicalized probabilistic context free grammar for German verb-final clauses. Grammar and formalism features which make the experiment feasible are described. Successive models ... More
Lexicalized Stochastic Modeling of Constraint-Based Grammars using Log-Linear Measures and EM TrainingAug 30 2000We present a new approach to stochastic modeling of constraint-based grammars that is based on log-linear models and uses EM for estimation from unannotated data. The techniques are applied to an LFG grammar for German. Evaluation on an exact match task ... More
Modulated X-ray Emissivity near the Stress Edge in Sgr A*Apr 17 2008Sgr A* is thought to be the radiative manifestation of a ~3.6E6 Msun supermassive black hole at the Galactic center. Its mm/sub-mm spectrum and its flare emission at IR and X-ray wavelengths may be produced within the inner ten Schwarzschild radii of ... More
Thermodynamic formalism for transport coefficients with an application to the shear modulus and shear viscosityDec 07 2016We discuss Onsager's thermodynamic formalism for transport coefficients and apply it to the calculation of the shear modulus and shear viscosity of a monodisperse system of repulsive particles. We focus on the concept of extensive "distance" and intensive ... More
Direct experimental observation of the Frenkel line in supercritical neonAug 30 2016Supercritical fluids are considered to be structurally uniform with indistinguishable dynamic and thermodynamic properties across entire pressure temperature stability range. However, several recent studies suggest that the supercritical state may not ... More
Experimental evidence for pressure-induced first order transition in cerium nitride from B1 to B10 structure typeJan 16 2017The crystal structure of CeN was investigated up to pressures of 82 GPa, using diamond anvil cell powder X-ray diffraction in two experiments with He and Si-oil as the pressure transmitting media. In contrast to previous reports, we do not observe the ... More
On the quantifier-free dynamic complexity of ReachabilityJun 13 2013Jan 28 2015The dynamic complexity of the reachability query is studied in the dynamic complexity framework of Patnaik and Immerman, restricted to quantifier-free update formulas. It is shown that, with this restriction, the reachability query cannot be dynamically ... More
Sélection de la structure d'un perceptron multicouches pour la réduction dun modèle de simulation d'une scierieDec 05 2008Simulation is often used to evaluate the relevance of a Directing Program of Production (PDP) or to evaluate its impact on detailed sc\'enarii of scheduling. Within this framework, we propose to reduce the complexity of a model of simulation by exploiting ... More
Infinite reduced words and the Tits boundary of a Coxeter groupJan 05 2013Sep 18 2014Let (W,S) be a finite rank Coxeter system with W infinite. We prove that the limit weak order on the blocks of infinite reduced words of W is encoded by the topology of the Tits boundary of the Davis complex X of W. We consider many special cases, including ... More
An optimization principle for the computation of MHD equilibria in the solar coronaDec 21 2006AIMS: We develop an optimization principle for computing stationary MHD equilibria. METHODS: Our code for the self-consistent computation of the coronal magnetic fields and the coronal plasma uses non-force-free MHD equilibria. Previous versions of the ... More
Probabilistic Reasoning about Actions in Nonmonotonic Causal TheoriesOct 19 2012We present the language {m P}{cal C}+ for probabilistic reasoning about actions, which is a generalization of the action language {cal C}+ that allows to deal with probabilistic as well as nondeterministic effects of actions. We define a formal semantics ... More
Elagage d'un perceptron multicouches : utilisation de l'analyse de la variance de la sensibilité des paramètresDec 04 2008The stucture determination of a neural network for the modelisation of a system remain the core of the problem. Within this framework, we propose a pruning algorithm of the network based on the use of the analysis of the sensitivity of the variance of ... More
Two-Variable Logic with Two Order RelationsOct 07 2011Mar 03 2012It is shown that the finite satisfiability problem for two-variable logic over structures with one total preorder relation, its induced successor relation, one linear order relation and some further unary relations is EXPSPACE-complete. Actually, EXPSPACE-completeness ... More
Causes and Explanations in the Structural-Model Approach: Tractable CasesDec 12 2012In this paper, we continue our research on the algorithmic aspects of Halpern and Pearl's causes and explanations in the structural-model approach. To this end, we present new characterizations of weak causes for certain classes of causal models, which ... More
On the boundedness of an iteration involving points on the hypersphereJan 11 2010Oct 05 2010For a finite set of points $X$ on the unit hypersphere in $\mathbb{R}^d$ we consider the iteration $u_{i+1}=u_i+\chi_i$, where $\chi_i$ is the point of $X$ farthest from $u_i$. Restricting to the case where the origin is contained in the convex hull of ... More
Dynamic Conjunctive QueriesApr 05 2017The article investigates classes of queries maintainable by conjunctive queries (CQs) and their extensions and restrictions in the dynamic complexity framework of Patnaik and Immerman. Starting from the basic language of quantifier-free conjunctions of ... More
Nef reduction and anticanonical bundlesOct 31 2003We investigate the structure of smooth projective 3-folds X with -K_X nef and K_X^3=0.
kdecopula: An R Package for the Kernel Estimation of Copula DensitiesMar 14 2016May 14 2016We describe the R package kdecopula, which provides fast implementations of various kernel estimators for the copula density. Due to its several plotting options it is particularly useful for the exploratory analysis of dependence structures. It can be ... More
Geometric compactification of moduli spaces of half-translation structures on surfacesFeb 03 2016In this paper, we give an equivariant compactification of the space PFlat(S) of homothety classes of half-translation structures on a compact, connected, orientable surface S. We introduce the space PMix(S) of homothety classes of mixed structures on ... More
Matrix product purifications for canonical ensembles and quantum number distributionsJul 06 2016Matrix product purifications (MPP) are a very efficient tool for the simulation of strongly correlated quantum many-body systems at finite temperatures. When a system features symmetries, these can be used to reduce computation costs substantially. It ... More
Compressed Sensing with Nonlinear Observations and Related Nonlinear Optimisation ProblemsMay 08 2012Non-convex constraints have recently proven a valuable tool in many optimisation problems. In particular sparsity constraints have had a significant impact on sampling theory, where they are used in Compressed Sensing and allow structured signals to be ... More
Does the wavefunction of the universe exist?Apr 07 2004Jun 02 2004The overwhelming majority of scientists still takes it for granted that classical mechanics (ClM) is nothing but a limiting case of quantum mechanics (QM). Although some physicists restrict this belief to a generalized QM as represented, e. g., by the ... More
Asymptotics of robust utility maximizationMar 06 2012For a stochastic factor model we maximize the long-term growth rate of robust expected power utility with parameter $\lambda\in(0,1)$. Using duality methods the problem is reformulated as an infinite time horizon, risk-sensitive control problem. Our results ... More
On the concept of (homo)morphism : a key notion in the learning of abstract algebraMar 28 2013This article is dedicated to the investigation of difficulties involved in the understanding of the homomorphism concept. It doesn't restrict to group-theory but on the contrary raises the issue of developing teaching strategies aiming at gaining access ... More
Hessian corrections to the Metropolis Adjusted Langevin AlgorithmJul 22 2015A natural method for the introduction of second-order derivatives of the log likelihood into MCMC algorithms is introduced, based on Taylor expansion of the Langevin equation followed by exact solution of the truncated system.
Twisted filtrations of Soergel bimodules and linear Rouquier complexesJan 03 2016We consider twisted standard filtrations of Soergel bimodules associated to arbitrary Coxeter groups and show that the graded multiplicities in these filtrations can be interpreted as structure constants in the Hecke algebra. This corresponds to the positivity ... More
Ramanujan's HeirsMar 20 2012Mar 27 2012Prof. Dr. Richard Dipper initiated the Summer School 1998 with Dr. Bernd Ackermann at the University of Stuttgart a year after Ramanujan's "lost notebook" had been published. The prime numbers needed in the representation theory of $\mathfrak{S}_{n}$ ... More
A note on entropy estimationMar 19 2015Jun 05 2015We compare an entropy estimator $H_z$ recently discussed in [10] with two estimators $H_1$ and $H_2$ introduced in [6][7]. We prove the identity $H_z \equiv H_1$, which has not been taken into account in [10]. Then, we prove that the statistical bias ... More
MPPhys - A many-particle simulation package for computational physics educationMar 07 2014In a first course to classical mechanics elementary physical processes like elastic two-body collisions, the mass-spring model, or the gravitational two-body problem are discussed in detail. The continuation to many-body systems, however, is defered to ... More
Solution of the Mayan Calendar EnigmaJan 13 2016Oct 26 2016Based on a purely arithmetical model of naked-eye astronomy, a calendar super-number N is calculated as the least common multiple of 9 astronomical parameters: the solar year, the three lunar months (the pentalunex and the two lunar semesters) and the ... More
Yangian Superalgebras in Conformal Field TheoryNov 30 2010Dec 07 2010Quantum Yangian symmetry in several sigma models with supergroup or supercoset as target is established. Starting with a two-dimensional conformal field theory that has current symmetry of a Lie superalgebra with vanishing Killing form we construct non-local ... More
Precise evaluation of thermal response functions by optimized density matrix renormalization group schemesJan 10 2013Jul 17 2013This paper provides a study and discussion of earlier as well as novel more efficient schemes for the precise evaluation of finite-temperature response functions of strongly correlated quantum systems in the framework of the time-dependent density matrix ... More
Numerical study of a three-dimensional generalized stadium billiardSep 17 1999May 04 2000We study a generalized three-dimensional stadium billiard and present strong numerical evidence that this system is completely chaotic. In this convex billiard chaos is generated by the defocusing mechanism. The construction of this billiard uses cylindrical ... More
Lyapunov exponents and Kolmogorov-Sinai entropy for a high-dimensional convex billiardSep 06 1999We compute the Lyapunov exponents and the Kolmogorov-Sinai (KS) entropy for a self-bound N-body system that is realized as a convex billiard. This system exhibits truly high-dimensional chaos, and 2N-4 Lyapunov exponents are found to be positive. The ... More
Universal solutions for interacting bosons in one-dimensional harmonic trapsAug 28 2001We consider systems of interacting bosons confined to one-dimensional harmonic traps. In the limit of perturbatively weak two-body interactions the system exhibits several universal states that are exact solutions for a large class of two-body interactions. ... More
Target-Superspace in 2d Dilatonic SupergravityJun 29 1999The N=1 supersymmetric version of generalized 2d dilaton gravity can be cast into the form of a Poisson Sigma Model, where the target space and its Poisson bracket are graded. The target space consists of a 1+1 superspace and the dilaton, which is the ... More
High energy scattering amplitudes in matrix string theoryMay 12 1999Mar 15 2000High energy fixed angle scattering is studied in matrix string theory. The saddle point world sheet configurations, which give the dominant contributions to the string theory amplitude, are taken as classical backgrounds in matrix string theory. A one ... More
Towards a Mori theory on compact Kaehler threefolds,IIFeb 04 1998We prove the existence of a Mori contraction on a compact Kaehler threefold whose canonical bundle is (analytically) not nef if the threefold can be approximated by projective threefolds or if the algebraic dimension is 2.
Non-Central Multivariate Chi-Square and Gamma DistributionsApr 23 2016Jul 05 2016A (p-1)-variate integral representation is given for the cumulative distribution function of the general p-variate non-central gamma distribution with a non-centrality matrix of any admissible rank. The real part of products of well known analytical functions ... More
Algebraic K-Theory of infinity-OperadsMar 09 2013Sep 03 2014The theory of dendroidal sets has been developed to serve as a combinatorial model for homotopy coherent operads by Moerdijk and Weiss. An infinity-operad is a dendroidal set D satisfying certain lifting conditions. In this paper we give a definition ... More
A multidimensional continued fraction generalization of Stern's diatomic sequenceJun 28 2012Sep 10 2013Continued fractions are linked to Stern's diatomic sequence 0,1,1,2,1,3,2,3,1,4,... (given by the recursion relation a_2n=a_n and a_{2n+1} = a_n + a_{n+1}, where a_0=0 and a_1=1), which has long been known. Using a particular multidimensional continued ... More
Measuring Information TransferJan 19 2000An information theoretic measure is derived that quantifies the statistical coherence between systems evolving in time. The standard time delayed mutual information fails to distinguish information that is actually exchanged from shared information due ... More
Predicting trend reversals using market instantaneous stateOct 30 2013Mar 03 2014Collective behaviours taking place in financial markets reveal strongly correlated states especially during a crisis period. A natural hypothesis is that trend reversals are also driven by mutual influences between the different stock exchanges. Using ... More
Effective Theory for Heavy QuarksJun 11 1996In this series of lectures the basic ideas of the $1/m_Q$ expansion in QCD ($m_Q$ is the mass of a heavy quark) are outlined. Applications to exclusive and inclusive decays are given.
Review of Heavy Quark Effective TheoryNov 25 1996A short review of a few selected topics in Heavy Quark Effective Theory is given. Applications to exclusive decays are discussed.
Weak Decays of Heavy-Quark SystemsMay 23 1994The recent theoretical progress in the description of semileptonic decays in the framework of the heavy mass expansion is summarized. Both inclusive and exclusive decays are considered.
An arbitrarily distortable Banach spaceApr 03 1991In this work we construct a ``Tsirelson like Banach space'' which is arbitrarily distortable.
The Grothendieck-Teichmüller group action on differential forms and formality morphism of chainsAug 28 2013Jan 14 2014It is known that one can associate a Kontsevich-type formality morphism to every Drinfeld associator. We show that this morphism may be extended to a Kontsevich-Shoikhet formality morphism of cochains and chains, by describing the action of the Grothendieck-Teichm\"uller ... More
Stable cohomology of polyvector fieldsOct 17 2011Dec 03 2014We show that the stable cohomology of the algebraic polyvector fields on $\mathbb{R}^n$, with values in the adjoint representation is the symmetric product space on the cohomology of M. Kontsevich's graph complex, up to some known classes.
CP-stability and the local lifting propertyJul 14 2015The purpose of this note is to discuss the local lifting property in terms of an equivalent approximation-type property, CP-stability, which was formulated by the author and Isaac Goldbring for the purposes of studying the continuous model theory of C$^*$-algebras ... More
Three-dimensional analytical magnetohydrostatic equilibria of rigidly rotating magnetospheres in cylindrical geometryJun 04 2009We present three-dimensional solutions of the magnetohydrostatic equations in the co-rotating frame of reference outside a magnetized rigidly rotating cylinder. We make no symmetry assumption for the magnetic field, but to be able to make analytical progress ... More
On Non-Relativistic Conformal Field Theory and Trapped Atoms: Virial Theorems and the State-Operator Correspondence in Three DimensionsDec 06 2007The field theory of nonrelativistic fermions interacting via contact interactions can be used to calculate the properties of few-body systems of cold atoms confined in harmonic traps. The state-operator correspondence of Non-Relativistic Conformal Field ... More
Leptoproduction of J/ψOct 26 1998I review the status of the extraction of NRQCD color-octet $J/\psi$ production matrix elements. Large theoretical uncertainties in current extractions from hadroproduction and photoproduction are emphasized. Leptoproduction of $J/\psi$ is calculated within ... More
Discussion on Peshkov et al., "Boltzmann-Ginzburg-Landau approach for continuous descriptions of generic Vicsek-like models"Apr 28 2014A discussion on the contribution of Peshkov, Bertin, Ginelli and Chate, arxiv:1404.3275v1, in this special issue.
Kinetic Theory of Flocking: Derivation of Hydrodynamic EquationsJun 09 2010Dec 03 2010It is shown how to explicitly coarse-grain the microscopic dynamics of the Vicsek model for self-propelled agents. The macroscopic transport equations are derived by means of an Enskog-type kinetic theory. Expressions for all transport coefficients at ... More
Electroweak Baryogenesis in the nMSSMOct 30 2006In this talk, electroweak baryogenesis in the nMSSM is discussed. We focus on differences compared to the MSSM. We conclude that electroweak baryogenesis in the nMSSM is rather generic. Still, sfermions of the first two generations are required to be ... More
QCD and High Energy Interactions: Moriond 2014 Theory SummaryJun 20 2014This article summarizes new theoretical developments, ideas and results that were presented at the 2014 Moriond "QCD and High Energy Interactions".
Successful strategies for a queens placing game on an n x n chess boardDec 18 2013Apr 21 2014In his list of open problems, Martin Erickson described a certain game: "Two players alternately put queens on an n x n chess board so that each new queen is not in range of any queen already on the board (the color of the queens is unimportant). The ... More
One loop matching coefficients for a variant overlap action--and some of its simpler relativesOct 16 2002I present one-loop perturbative calculations of matching coefficients between matrix elements in continuum regulated QCD and lattice QCD with overlap fermions, with emphasis a recently-proposed variant discretization of the overlap. These fermions have ... More
Another determination of the quark condensate from an overlap actionJul 18 2001Jul 24 2001I use the technique of Hernandez, et al (hep-lat/0106011) to convert a recent calculation of the lattice-regulated quark condensate from an overlap action to a continuum-regulated number. I find Sigma(MSbar)(mu = 2 GeV) = (282(6) MeV)-cubed times (a-inverse/1766 ... More
Particle Correlations at LEPJan 30 2002Particle correlations are extensively studied to obtain information about the dynamics of hadron production. From 1989 to 2000 the four LEP collaborations recorded more than 16 million hadronic Z0 decays and several thousand W+W- events. In Z0 decays, ... More
Anthropomorphic Quantum Darwinism as an explanation for ClassicalityJun 15 2009According to the so-called ``Quantum Darwinist'' approach, the emergence of ``classical islands'' from a quantum background is assumed to obey a (selection) principle of maximal information. We illustrate this idea by considering the coupling of two particles ... More
Comment on ``A local hidden variable model of quantum correlations exploiting the detection loophole''Jul 20 1999We study in this short comment the analogies and the differences that exist between several local hidden variable models.
A new expression for mutually unbiased bases in prime power dimensionsSep 15 2004Nov 26 2004Mutually unbiased bases generalize the X, Y and Z qubit bases. They possess numerous applications in quantum information science. It is well-known that in prime power dimensions N=p^m (with p prime and m a positive integer) there exists a maximal set ... More
Mapping the vacuum structure of gauged maximal supergravities: an application of high-performance symbolic algebraMay 20 2003The analysis of the extremal structure of the scalar potentials of gauged maximally extended supergravity models in five, four, and three dimensions, and hence the determination of possible vacuum states of these models is a computationally challenging ... More
Introducing LambdaTensor1.0 - A package for explicit symbolic and numeric Lie algebra and Lie group calculationsAug 29 2002Mar 26 2003Due to the occurrence of large exceptional Lie groups in supergravity, calculations involving explicit Lie algebra and Lie group element manipulations easily become very complicated and hence also error-prone if done by hand. Research on the extremal ... More
Some stationary points of gauged N=16 D=3 supergravityJan 05 2002Five nontrivial stationary points are found for maximal gauged N=16 supergravity in three dimensions with gauge group $SO(8)\times SO(8)$ by restricting the potential to a submanifold of the space of $SU(3)\subset(SO(8)\times SO(8))_{\rm diag}$ singlets. ... More
The many vacua of gauged extended supergravitiesNov 12 2008A novel method is presented which employs advanced numerical techniques used in the engineering sciences to find and study the properties of nontrivial vacua of gauged extended supergravity models. While this method only produces approximate numerical ... More
Rare region effects at classical, quantum, and non-equilibrium phase transitionsFeb 13 2006May 16 2006Rare regions, i.e., rare large spatial disorder fluctuations, can dramatically change the properties of a phase transition in a quenched disordered system. In generic classical equilibrium systems, they lead to an essential singularity, the so-called ... More
Quantum phase transitionsOct 19 2000Phase transitions which occur at zero temperature when some non-thermal parameter like pressure, chemical composition or magnetic field is changed are called quantum phase transitions. They are caused by quantum fluctuations which are a consequence of ... More
Chaotic behavior and damage spreading in the Glauber Ising model - a master equation approachNov 28 1996We investigate the sensitivity of the time evolution of a kinetic Ising model with Glauber dynamics against the initial conditions. To do so we apply the "damage spreading" method, i.e., we study the simultaneous evolution of two identical systems subjected ... More
On duality of algebraic quantum groupoidsMay 20 2016Like quantum groups, quantum groupoids frequently appear in pairs of mutually dual objects. We develop a general Pontrjagin duality theory for quantum groupoids in the algebraic setting that extends Van Daele's duality theory for multiplier Hopf algebras ... More
The matching polytope has exponential extension complexityNov 11 2013Nov 23 2015A popular method in combinatorial optimization is to express polytopes P, which may potentially have exponentially many facets, as solutions of linear programs that use few extra variables to reduce the number of constraints down to a polynomial. After ... More
Neural networks with differentiable structureJun 20 2016Aug 06 2016While gradient descent has proven highly successful in learning connection weights for neural networks, the actual structure of these networks is usually determined by hand, or by other optimization algorithms. Here we describe a simple method to make ... More
OTTER Experiments in a System of Combinatory LogicSep 02 1994This paper describes some experiments involving the automated theorem-proving program OTTER in the system TRC of illative combinatory logic. We show how OTTER can be steered to find a contradiction in an inconsistent variant of TRC, and present some experimentally ... More
New Solutions of the Einstein-Dirac Equation in Dimension n=3Jan 27 2000The aim of this short note is to announce the existence of a one-parameter family of left-invariant metrics on $S^3$ admitting WK-spinors. This family contains the two non-Einstein Sasakian metrics with WK-spinors on $S^3$, but does not contain the standard ... More
Introduction to String TheoryJul 27 2002We give a pedagogical introduction to string theory, D-branes and p-brane solutions.
GKM sheaves and nonorientable surface group representationsAug 09 2010Apr 25 2013Let T be a compact torus and X a nice compact T-space (say a manifold or variety). We introduce a functor assigning to X a "GKM-sheaf" F_X over a "GKM-hypergraph" G_X. Under the condition that X is equivariantly formal, the ring of global sections of ... More
The moduli space of flat SU(2)-bundles over a nonorientable surfaceJun 11 2008Dec 31 2008We study the topology of the moduli space of flat SU(2)-bundles over a nonorientable surface X. This moduli space may be identified with the space of homomorphisms Hom(\pi_1(X),SU(2)) modulo conjugation by SU(2). In particular, we compute the (rational) ... More
The physics of volume renderingOct 22 2014Radiation transfer is an important topic in several physical disciplines, probably most prominently in astrophysics. Computer scientists use radiation transfer, among other things, for the visualisation of complex data sets with direct volume rendering. ... More
Data selection and confounding in the court case of Lucia de BerkAug 10 2007The nurse Lucia de Berk was convicted by the Dutch courts as a serial killer with 7 murders and 3 attempts at murder in three hospitals where she worked. The nurse however always professed her innocence and indeed was never observed in such an act of ... More
Coquet: a Coq library for verifying hardwareAug 22 2011We propose a new library to model and verify hardware circuits in the Coq proof assistant. This library allows one to easily build circuits by following the usual pen-and-paper diagrams. We define a deep-embedding: we use a (dependently typed) data-type ... More
Retraction of 'Elementary proof of the Giuga-Agoh conjecture'Jun 08 2011Jun 09 2011An elementary gap in the proof of corollary 2.2 was found, the claim in the first version of the paper is thus retracted.
Application of second generation wavelets to blind spherical deconvolutionJan 15 2013We adress the problem of spherical deconvolution in a non parametric statistical framework, where both the signal and the operator kernel are subject to error measurements. After a preliminary treatment of the kernel, we apply a thresholding procedure ... More
On the Applicability of Post's LatticeJul 17 2010Jan 05 2012For decision problems P defined over Boolean circuits from a restricted set of gates, we have that P(B) AC0 many-one reduces to P(B') for all finite sets B and B' of gates such that all gates from B can be computed by circuits over gates from B'. In this ... More
Fitted and unfitted domain decomposition using penalty free Nitsche method for the Poisson problem with discontinuous material parametersSep 02 2015In this paper, we study the stability of the non symmetric version of the Nitsche's method without penalty for domain decomposition. The Poisson problem is considered as a model problem. The computational domain is divided into two subdomain that can ... More
Constructing the ordinary character tables of some Atlas groups using character theoretic methodsApr 04 2016May 12 2016We compute the character tables of the following groups with character theoretic methods, using known information about the conjugacy classes and about the character tables of some subgroups and factor groups: $Th$, $J_4$, $2.{}^2E_6(2)$, $2.{}^2E_6(2).2$, ... More
Upscaling a model for the thermally-driven motion of screw dislocationsSep 29 2015Jul 19 2016We formulate and study a stochastic model for the thermally-driven motion of interacting straight screw dislocations in a cylindrical domain with a convex polygonal cross-section. Motion is modelled as a Markov jump process, where waiting times for transitions ... More
Color SuperconductivityNov 03 1999We discuss recent results on color superconductivity in QCD at large chemical potential.
Curvature-adapted submanifolds of symmetric spacesFeb 23 2011Feb 20 2012We study curvature-adapted submanifolds of general symmetric spaces. We generalize Cartan's theorem for isoparametric hypersurfaces of spheres and Wang's classification of isoparametric Hopf hypersurfaces in complex projective spaces to any compact symmetric ... More
Quantum Chromodynamics: Computational AspectsAug 19 2016We present a brief introduction to QCD, the QCD phase diagram, and non-equilibrium phenomena in QCD. We emphasize aspects of the theory that can be addressed using computational methods, in particular euclidean path integral Monte Carlo, fluid dynamics, ... More