Results for "Thomas Ehrhard"

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CCS for TreesJun 07 2013CCS can be considered as a most natural extension of finite state automata in which interaction is made possible thanks to parallel composition. We propose here a similar extension for top-down tree automata. We introduce a parallel composition which ... More
Differentials and distances in probabilistic coherence spacesFeb 13 2019In probabilistic coherence spaces, a denotational model of probabilistic functional languages, mor-phisms are analytic and therefore smooth. We explore two related applications of the corresponding derivatives. First we show how derivatives allow to compute ... More
An introduction to Differential Linear Logic: proof-nets, models and antiderivativesJun 06 2016Differential Linear Logic enriches Linear Logic with additional logical rules for the exponential connectives, dual to the usual rules of dereliction, weakening and contraction. We present a proof-net syntax for Differential Linear Logic and a categorical ... More
A finiteness structure on resource termsJan 19 2010In our paper "Uniformity and the Taylor expansion of ordinary lambda-terms" (with Laurent Regnier), we studied a translation of lambda-terms as infinite linear combinations of resource lambda-terms, from a calculus similar to Boudol's lambda-calculus ... More
Probabilistic call by push valueJul 16 2016We introduce a probabilistic extension of Levy's Call-By-Push-Value. This extension consists simply in adding a " flipping coin " boolean closed atomic expression. This language can be understood as a major generalization of Scott's PCF encompassing both ... More
Acyclic Solos and Differential Interaction NetsJul 01 2010Sep 01 2010We present a restriction of the solos calculus which is stable under reduction and expressive enough to contain an encoding of the pi-calculus. As a consequence, it is shown that equalizing names that are already equal is not required by the encoding ... More
Probabilistic call by push valueJul 16 2016Jan 08 2019We introduce a probabilistic extension of Levy's Call-By-Push-Value. This extension consists simply in adding a " flipping coin " boolean closed atomic expression. This language can be understood as a major generalization of Scott's PCF encompassing both ... More
On the denotational semantics of Linear Logic with least and greatest fixed points of formulasJun 13 2019We develop a denotational semantics of Linear Logic with least and greatest fixed points in coherence spaces (where both fixed points are interpreted in the same way) and in coherence spaces with totality (where they have different interpretations). These ... More
The stack calculusMar 29 2013We introduce a functional calculus with simple syntax and operational semantics in which the calculi introduced so far in the Curry-Howard correspondence for Classical Logic can be faithfully encoded. Our calculus enjoys confluence without any restriction. ... More
Full abstraction for probabilistic PCFNov 04 2015We present a probabilistic version of PCF, a well-known simply typed universal functional language. The type hierarchy is based on a single ground type of natural numbers. Even if the language is globally call-by-name, we allow a call-by-value evaluation ... More
A convenient differential categoryJun 16 2010In this paper, we show that the category of Mackey-complete, separated, topological convex bornological vector spaces and bornological linear maps is a differential category. Such spaces were introduced by Fr\"olicher and Kriegl, where they were called ... More
Measurable Cones and Stable, Measurable FunctionsNov 27 2017We define a notion of stable and measurable map between cones endowed with measurability tests and show that it forms a cpo-enriched cartesian closed category. This category gives a denotational model of an extension of PCF supporting the main primitives ... More
A Fully Abstract Semantics for Value-passing CCS for TreesJul 01 2016This paper provides a fully abstract semantics for value-passing CCS for trees (VCCTS). The operational semantics is given both in terms of a reduction semantics and in terms of a labelled transition semantics. The labelled transition semantics is non-sequential, ... More
Full Abstraction for the Resource Lambda Calculus with Tests, through Taylor ExpansionSep 13 2012Oct 08 2012We study the semantics of a resource-sensitive extension of the lambda calculus in a canonical reflexive object of a category of sets and relations, a relational version of Scott's original model of the pure lambda calculus. This calculus is related to ... More
New proofs of Rosenthal's $\ell^{1}$--theorem and the Josefson--Nissenzweig theoremMar 31 1994We give elementary proofs of the theorems mentioned in the title. Our methods rely on a simple version of Ramsey theory and a martingale difference lemma. They also provide quantitative results: if a Banach space contains $\ell^{1}$ only with a bad constant ... More
Proceedings Joint International Workshop on Linearity & Trends in Linear Logic and ApplicationsApr 12 2019This volume contains a selection of papers presented at Linearity/TLLA 2018: Joint Linearity and TLLA workshops (part of FLOC 2018) held on July 7-8, 2018 in Oxford. Linearity has been a key feature in several lines of research in both theoretical and ... More
On Linear Information SystemsMar 29 2010Scott's information systems provide a categorically equivalent, intensional description of Scott domains and continuous functions. Following a well established pattern in denotational semantics, we define a linear version of information systems, providing ... 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
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
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.
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
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
Spectral Correlations in the Crossover Transition from a Superposition of Harmonic Oscillators to the Gaussian Unitary EnsembleJul 20 1998We compute the spectral correlation functions for the transition from a harmonic oscillator towards the Gaussian Unitary Ensemble (GUE). We use a variant of the supersymmetry method to obtain analytical results in a fast and elegant way. In contrast to ... 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
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
Gluon sivers and experimental considerations for TMDsDec 14 2012The study and characterisation of transverse-momentum-dependent distribution functions (TMDs) is a major goal of the Electron-Ion Collider (EIC) physics programme. The study of gluon TMDs poses a greater challenge than for quark TMDs in DIS measurements, ... More
Strong-Field QED and High Power LasersNov 22 2011This contribution presents an overview of fundamental QED processes in the presence of an external field produced by an ultra-intense laser. The discussion focusses on the basic intensity effects on vacuum polarisation and the prospects for their observation. ... More
Predictions of Physical Observables from Minimal Neutrino StructuresJul 31 2003We find all possible seesaw textures which can describe in a natural way the currently observed neutrino oscillation pattern in terms of a minimum number of parameters. Natural here means due only to the relative smallness (vanishing) of some parameters ... More
Charged lepton flavor violation and the origin of neutrino massesDec 18 2013The neutrino oscillations imply that charged lepton flavor violation (CLFV) processes do exist. Even if the associated rates are in general expected very suppressed, it turns out that this is not always necessarily the case. In the framework of the three ... More
Leptogenesis at the TeV scaleNov 08 2001Apr 16 2002We present a general description of the problems encountered when attempting to build a simple model of leptogenesis and hence of baryogenesis at an energy scale as low as 1-10 TeV. We consider three possible lepton asymmetry enhancement mechanisms in ... More
The exact packing measure of Lévy treesAug 01 2010We study fine properties of L\'evy trees that are random compact metric spaces introduced by Le Gall and Le Jan in 1998 as the genealogy of continuous state branching processes. L\'evy trees are the scaling limits of Galton-Watson trees and they generalize ... More
Packing and Hausdorff measures of stable treesJan 29 2010In this paper we discuss Hausdorff and packing measures of random continuous trees called stable trees. Stable trees form a specific class of L\'evy trees (introduced by Le Gall and Le Jan in 1998) that contains Aldous's continuum random tree (1991) which ... More
Mittag-Leffler functions and complete monotonicityDec 16 2013Dec 17 2013We consider two operations on the Mittag-Leffler function which cancel the exponential term in the expansion at infinity, and generate a completely monotonic function. The first one is the action of a certain differential-difference operator, and leads ... More
Comparing Fréchet and positive stable lawsOct 07 2013Jan 27 2014Let ${\bf L}$ be the unit exponential random variable and ${\bf Z}_\alpha$ the standard positive $\alpha$-stable random variable. We prove that $\{(1-\alpha) \alpha^{\gamma_\alpha} {\bf Z}_\alpha^{-\gamma_\alpha}, 0< \alpha <1\}$ is decreasing for the ... More
Total positivity of a Cauchy kernelMay 06 2013We study the total positivity of the kernel $1/(x^2 + 2 \cos(\pi\a)xy +y^2).$ The case of infinite order is characterized by an application of Schoenberg's theorem. We then give necessary conditions for the cases of any given finite order with the help ... More
Some issues concerning the proton charge radius puzzleJul 20 2012Oct 24 2012An explanation of the difference of the charge radius of the proton as determined from the Lamb shift in electronic hydrogen and from elastic electron scattering off the proton on the one side and the recent high precision determination with muonic hydrogen ... More
Calculation of the Electroelastic Green's Function of the Hexagonal Infinite MediumMar 10 2015The electroelastic 4 $\times$ 4 Green's function of a piezoelectric hexagonal (transversely isotropic) infinitely extended medium is calculated explicitly in closed compact form (eqs. (73) ff. and (88) ff., respectively) by using residue calculation. ... More
Taking back control of HPC file systems with Robinhood Policy EngineMay 06 2015Today, the largest Lustre file systems store billions of entries. On such systems, classic tools based on namespace scanning become unusable. Operations such as managing file lifetime, scheduling data copies, and generating overall filesystem statistics ... More
Orbits of curves under the Johnson kernelAug 23 2011Apr 07 2014This paper has two main goals. First, we give a complete, explicit, and computable solution to the problem of when two simple closed curves on a surface are equivalent under the Johnson kernel. Second, we show that the Johnson filtration and the Johnson ... More
Microscopic calculation of the 3He(alpha,gamma)7Be and 3H(alpha,gamma)7Li capture cross sections using realistic interactionsNov 12 2010Jan 25 2011The radiative capture cross sections for the 3He(alpha,gamma)7Be and 3H(alpha,gamma)7Li reactions are calculated in the fully microscopic fermionic molecular dynamics approach using a realistic effective interaction that reproduces the nucleon-nucleon ... More
Sources of false positives and false negatives in the STATCHECK algorithm: Reply to Nuijten et al. (2016)Oct 04 2016Nov 16 2016STATCHECK is an R algorithm designed to scan papers automatically for inconsistencies between test statistics and their associated p values (Nuijten et al., 2016). The goal of this comment is to point out an important and well-documented flaw in this ... More
Congruences for Convolutions of Hilbert Modular FormsJan 20 2012Let $\f$ be a primitive, cuspidal Hilbert modular form of parallel weight. We investigate the Rankin convolution $L$-values $L(\f,\g,s)$, where $\g$ is a theta-lift modular form corresponding to a finite-order character. We prove weak forms of Kato's ... More
Phase diagrams of 2D and 3D disordered Bose gases in the local density approximationOct 03 2012We study the superfluid transitions in bidimensional (2D) and tridimensional (3D) disordered and interacting Bose gases. We work in the limit of long-range correlated disorder such that it can be treated in the local density approximation. We present ... More
Contrasting influence of charged impurities on transport and gain in terahertz quantum cascade lasersOct 29 2015Transport and gain properties of a resonant-phonon terahertz quantum cascade laser are calculated using nonequilibrium Green's functions. Impurity scattering is shown to be responsible for contrasting nonlinear effects in the transport and the gain properties. ... More
Higher rank lattices cannot act on hyperbolic spacesJul 07 2016We prove that any action of a higher rank lattice on a Gromov-hyperbolic space is elementary. More precisely, it is either elliptic or parabolic. This is a large generalization of the fact that any action of a higher rank lattice on a tree has a fixed ... More
Constructive discrepancy minimization for convex setsApr 01 2014Apr 12 2016A classical theorem of Spencer shows that any set system with n sets and n elements admits a coloring of discrepancy O(n^1/2). Recent exciting work of Bansal, Lovett and Meka shows that such colorings can be found in polynomial time. In fact, the Lovett-Meka ... More
Laminations géodésiques platesNov 29 2013Sep 11 2014Since their introduction by Thurston, geodesic laminations on hyperbolic surfaces occur in many contexts. In this paper, we propose a generalization of geodesic laminations on locally CAT(0), complete, geodesic metric spaces, whose boundary at infinity ... More
Sampling and reconstructing signals from a union of linear subspacesNov 18 2009Dec 02 2009In this note we study the problem of sampling and reconstructing signals which are assumed to lie on or close to one of several subspaces of a Hilbert space. Importantly, we here consider a very general setting in which we allow infinitely many subspaces ... More
Algebraic moment closure for population dynamics on discrete structuresMay 15 2014Moment closure on general discrete structures often requires one of the following: (i) an absence of short closed loops (zero clustering); (ii) existence of a spatial scale; (iii) ad hoc assumptions. Algebraic methods are presented to avoid the use of ... More
The topology of positive scalar curvatureMay 16 2014Jun 25 2014In this survey article, given a smooth closed manifold M we study the space of Riemannian metrics of positive scalar curvature on M. A long-standing question is: when is this space non-empty (i.e. when does M admit a metric of positive scalar curvature)? ... More
Loop groups and string topologyFeb 26 2008Survey article on loop groups and their representations, following a course of three lectures held at the summer school "algebraic groups" at the Georg-August-Universitaet zu Goettingen, June 27--July 13, 2005. We discuss loop groups, their central extensions, ... More
Geometry of branes on supergroupsSep 02 2008In this note we analyze the geometry of maximally symmetric boundary conditions in Lie supergroup Wess-Zumino-Novikov-Witten models. We find that generically the worldvolume of a brane is a twisted superconjugacy class, very much like in the Lie group ... More
AA Dor - An Eclipsing sdOB - Brown Dwarf BinaryNov 25 2003AA Dor is an eclipsing, close, post common-envelope binary consisting of a sdOB primary star and an unseen secondary with an extraordinary small mass - formally a brown dwarf. The brown dwarf may have been a former planet which survived a common envelope ... More
Autoregressive Time Series Forecasting of Computational DemandNov 14 2007We study the predictive power of autoregressive moving average models when forecasting demand in two shared computational networks, PlanetLab and Tycoon. Demand in these networks is very volatile, and predictive techniques to plan usage in advance can ... More
Alexander varieties and largeness of finitely presented groupsMay 01 2012Let X be a finite CW complex. We show that the fundamental group of X is large if and only if there is a finite cover Y of X and a sequence of finite abelian covers \{Y_N\} of Y which satisfy b_1(Y_N)\geq N. We give some applications of this result to ... More
Isotopy invariants for closed braids and almost closed braids via loops in stratified spacesJun 19 2006Let $\phi : S^1\times D^2\to S^1$ be the natural projection. An oriented knot $K\hookrightarrow V = S^1\times D^2$ is called an almost closed braid if the restriction of $\phi$ to K has exactly two (non-degenerate) critical points (and K is a closed braid ... More
Gauge fields and interactions in matrix string theorySep 03 1997Sep 18 1997It is shown that all possible N sheeted coverings of the cylinder are contained in type IIA matrix string theory as non-trivial gauge field configurations. Using these gauge field configurations as backgrounds the large $N$ limit is shown to lead to the ... More
The D0-brane metric in N = 2 sigma modelsJun 30 2000Aug 07 2000We investigate the physical metric seen by a D0-brane probe in the background geometry of an N=2 sigma model. The metric is evaluated by calculating the Zamolodchikov metric for the disc two point function of the boundary operators corresponding to the ... More
Collective and chaotic motion in self-bound many-body systemsMay 06 1999Feb 28 2000We investigate the interplay of collective and chaotic motion in a classical self-bound N-body system with two-body interactions. This system displays a hierarchy of three well separated time scales that govern the onset of chaos, damping of collective ... More
Gravity in Two Spacetime DimensionsNov 27 2000In this habilitation thesis we provide an introduction to gravitational models in two spacetime dimensions. Focus is put on exactly solvable models. We begin by introducing and motivating different possible gravitational actions, including those of generalized ... More
All Symmetries of Non-Einsteinian Gravity in $d =2$Jul 01 1992Nov 24 1992The covariant form of the field equations for two--dimensional $R^2$--gravity with torsion as well as its Hamiltonian formulation are shown to suggest the choice of the light--cone gauge. Further a one--to--one correspondence between the Hamiltonian gauge ... More
New Tests of NRQCD from Quarkonia Within JetsJan 21 2016I review the current status of quarkonium production theory based on the non-relativistic QCD factorization formalism (NRQCD). While this theory describes much of the world's data on J/\psi and \Upsilon production, there are still outstanding problems, ... More
Charm production asymmetries from heavy-quark recombinationJun 19 2003Charm asymmetries in fixed-target hadroproduction experiments are sensitive to power corrections to the QCD factorization theorem for heavy quark production. A power correction called heavy-quark recombination has recently been proposed to explain these ... More
Scale Setting in Top Quark DecaysFeb 27 1996Jun 03 1996We compute the $O(\beta_0 \alpha_s^2)$ QCD corrections to the Standard Model decay $t\rightarrow W^+ b$ as well as the non standard decay $t\rightarrow H^+ b$. We then use our results to compute the BLM scale for these decays, and study the dependence ... More
Generalised canonical basic sets for Ariki-Koike algebrasMar 23 2013Jan 22 2014Let H be a non semi-simple Ariki-Koike algebra. According to [18] and [14], there is a generalisation of Lusztig's a-function which induces a natural order (parametrised by a tuple m) on Specht modules. In some cases, Geck and Jacon have proved that this ... More
Cytoskeleton and Cell MotilityMay 12 2011The present article is an invited contribution to the Encyclopedia of Complexity and System Science, Robert A. Meyers Ed., Springer New York (2009). It is a review of the biophysical mechanisms that underly cell motility. It mainly focuses on the eukaryotic ... More
Lectures On Black Hole Evaporation and Information LossDec 15 1994Trieste Spring School Lectures describing the author's opinions about black hole evaporation and information loss. The remnant, or cornucopion scenario for the endpoint of Hawking evaporation is described in detail. In this picture information can be ... More
Electroid varieties and a compactification of the space of electrical networksFeb 25 2014Oct 27 2014We construct a compactification of the space of circular planar electrical networks studied by Curtis-Ingerman-Morrow and De Verdiere-Gitler-Vertigan, using cactus networks. We embed this compactification as a linear slice of the totally nonnegative Grassmannian, ... More
Real difference Galois theoryJul 08 2015Jun 15 2016In this paper, we develop a difference Galois theory in the setting of real fields. After proving the existence and uniqueness of the real Picard-Vessiot extension, we define the real difference Galois group and prove a Galois correspondence.
Extremal conformal structures on projective surfacesOct 05 2015We introduce a new functional $\mathcal{E}_{\mathfrak{p}}$ on the space of conformal structures on an oriented projective manifold $(M,\mathfrak{p})$. The quantity $\mathcal{E}_{\mathfrak{p}}([g])\geq 0$ measures how much $\mathfrak{p}$ deviates from ... More
A novel approach to symbolic algebraJun 02 2004A prototype for an extensible interactive graphical term manipulation system is presented that combines pattern matching and nondeterministic evaluation to provide a convenient framework for doing tedious algebraic manipulations that so far had to be ... More
The one-flavor quark condensate and related problemsSep 20 2006I describe a recent calculation (by me, Hoffmann, Liu, and Schaefer) of the chiral condensate in one-flavor QCD using numerical simulations with overlap fermions. The condensate is extracted by fitting the distribution of low lying eigenmodes of the Dirac ... More
Lattice calculations of the spectroscopy of baryons with broken flavor SU(3) symmetry and 3, 5, or 7 colorsAug 19 2013Lattice Monte Carlo calculations of baryon spectroscopy in gauge groups SU(N), N=3, 5, 7, are presented. The quenched valence fermions come in three flavors, two degenerate mass ones and a third heavier flavor. The data shows striking regularities reminiscent ... More
Arbitrary Rotation Invariant Random Matrix Ensembles and SupersymmetryJun 03 2006We generalize the supersymmetry method in Random Matrix Theory to arbitrary rotation invariant ensembles. Our exact approach further extends a previous contribution in which we constructed a supersymmetric representation for the class of norm-dependent ... More
Norm-dependent Random Matrix Ensembles in External Field and SupersymmetryJun 03 2006The class of norm-dependent Random Matrix Ensembles is studied in the presence of an external field. The probability density in those ensembles depends on the trace of the squared random matrices, but is otherwise arbitrary. An exact mapping to superspace ... More
Advection-Dominated Accretion with Infall and OutflowsMar 22 2000We present self-similar solutions for advection-dominated accretion flows with radial viscous force in the presence of outflows from the accretion flow or infall. The axisymmetric flow is treated in variables integrated over polar sections and the effects ... More
Correlations of decay times of entangled composite unstable systemsApr 19 2012The role played by Time in the quantum theory is still mysterious by many aspects. In particular it is not clear today whether the distribution of decay times of unstable particles could be described by a Time Operator. As we shall discuss, different ... More
Quantum entanglement, interaction, and the classical limitJan 20 2004Two or more quantum systems are said to be in an entangled or non-factorisable state if their joint (supposedly pure) wave-function is not expressible as a product of individual wave functions but is instead a superposition of product states. It is only ... More
Boundary observability of gravity water wavesJun 29 2015Consider a three-dimensional fluid in a rectangular tank, bounded by a flat bottom, vertical walls and a free surface evolving under the influence of gravity. We prove that one can estimate its energy by looking only at the motion of the points of contact ... More
Large Deviation For Outlying Coordinates in Beta EnsemblesApr 04 2013Jan 12 2014For Y a subset of the complex plane,a beta ensemble is a sequence of probability measures on Y^n for n=1,2,3...depending on a real-valued continuous function Q and a real positive parameter beta.We consider the associated sequence of probability measures ... More
Translation invariant equations and the method of SandersJul 06 2011Jan 30 2012We extend the recent improvement of Roth's theorem on three term arithmetic progressions by Sanders to obtain similar results for the problem of locating non-trivial solutions to translation invariant linear equations in many variables in both $\bbz/N\bbz$ ... More
Stabilization of gravity water wavesMar 28 2016This paper is devoted to the stabilization of the incompressible Euler equation with free surface. We study the damping of two-dimensional gravity waves by an absorbing beach where the water-wave energy is dissipated by using the variations of the external ... More
Thermal expansion and Grueneisen parameter in quantum Griffiths phasesMay 13 2009Jul 16 2009We consider the behavior of the Gr\"{u}neisen parameter, the ratio between thermal expansion and specific heat, at pressure-tuned infinite-randomness quantum-critical points and in the associated quantum Griffiths phases. We find that the Gr\"{u}neisen ... More
Computing quantum phase transitionsSep 06 2007This article first gives a concise introduction to quantum phase transitions, emphasizing similarities with and differences to classical thermal transitions. After pointing out the computational challenges posed by quantum phase transitions, a number ... More
Monte-Carlo simulations of the clean and disordered contact process in three dimensionsSep 06 2012Nov 30 2012The absorbing-state transition in the three-dimensional contact process with and without quenched randomness is investigated by means of Monte-Carlo simulations. In the clean case, a reweighting technique is combined with a careful extrapolation of the ... More
In an Ising model with spin-exchange dynamics damage always spreadsMar 04 1998Aug 06 1998We investigate the spreading of damage in Ising models with Kawasaki spin-exchange dynamics which conserves the magnetization. We first modify a recent master equation approach to account for dynamic rules involving more than a single site. We then derive ... More
Damage spreading in random field systemsMay 29 1997We investigate how a quenched random field influences the damage spreading transition in kinetic Ising models. To this end we generalize a recent master equation approach and derive an effective field theory for damage spreading in random field systems. ... More
Blow up Analysis for Anomalous Granular GasesApr 27 2011May 07 2012We investigate in this article the long-time behaviour of the solutions to the energy-dependant, spatially-homogeneous, inelastic Boltzmann equation for hard spheres. This model describes a diluted gas composed of hard spheres under statistical description, ... More
Cocalibrated G_2-manifolds with Ricci flat characteristic connectionMar 29 2013Any 7-dimensional cocalibrated G_2-manifold admits a unique connection $\nabla$ with skew symmetric torsion. We study these manifolds under the additional condition that the $\nabla$-Ricci tensor vanishes. In particular, we describe their geometry in ... More
Strings, higher curvature corrections, and black holesDec 05 2005We review old and recent results on subleading contributions to black hole entropy in string theory.
Black Hole Entropy, Special Geometry and StringsJul 25 2000Sep 30 2000We review work done over the last years on the macroscopic and microscopic entropy of supersymmetric black holes in fourdimensional N=2 supergravity and in N=2 compactifications of string theory and M-theory. Particular emphasis is put on the crucial ... More
Topological Transitions and Enhancon-like Geometries in Calabi-Yau Compactifications of M-TheoryDec 17 2002We study the impact of topological phase transitions of the internal Calabi-Yau threefold on the space-time geometry of five-dimensional extremal black holes and black strings. For flop transitions and SU(2) gauge symmetry enhancement we show that solutions ... More
Black Holes in Supergravity and String TheoryApr 13 2000Apr 20 2000We give an elementary introduction to black holes in supergravity and string theory. The focus is on BPS solutions in four- and higher-dimensional supergravity and string theory. Basic ideas and techniques are explained in detail, including exercises ... More
A short proof of the irreflexivity conjectureApr 15 1992Gives a short proof of Dehornoy's latest result. The same simple argument (and more) was discovered by Laver's student Larue.
On Gödel's second incompleteness theoremApr 15 1992A very short proof of G\"odel's second incompleteness theorem (for set theory, second order arithmetic etc.)