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TSViz: Demystification of Deep Learning Models for Time-Series AnalysisFeb 08 2018This paper presents a novel framework for demystification of convolutional deep learning models for time series analysis. This is a step towards making informed/explainable decisions in the domain of time series, powered by deep learning. There have been ... More

Classical solutions in the Einstein-Born-Infeld-Abelian-Higgs modelFeb 01 2001Feb 20 2001We consider the classical equations of the Born-Infeld-Abelian-Higgs model (with and without coupling to gravity) in an axially symmetric ansatz. A numerical analysis of the equations reveals that the (gravitating) Nielsen-Olesen vortices are smoothly ... More

A random shock model with mixed effect, including competing soft and sudden failures, and dependenceSep 02 2014A system is considered, which is subject to external and possibly fatal shocks, with dependence between the fatality of a shock and the system age. Apart from these shocks, the system suffers from competing soft and sudden failures, where soft failures ... More

An algorithm (CoDeFi) for the curse of dimensionality in financeJun 30 2016We present a new algorithm (CoDeFi) to tackle the Curse Of Dimensionality In Finance and deal with a broad class of partial differential equations including the Kolmogorov equations as, for instance, the Black and Scholes equations. As a main feature, ... More

Decomposition of time-covariant operations on quantum systems with continuous and/or discrete energy spectrumJul 19 2004Sep 30 2004Every completely positive map G that commutes which the Hamiltonian time evolution is an integral or sum over (densely defined) CP-maps G_\sigma where \sigma is the energy that is transferred to or taken from the environment. If the spectrum is non-degenerated ... More

A nonparametric test for a constant correlation matrixOct 04 2012Oct 27 2014We propose a nonparametric procedure to test for changes in correlation matrices at an unknown point in time. The new test requires only mild assumptions on the serial dependence structure and has considerable power in finite samples. We derive the asymptotic ... More

(g-2)_mu and supersymmetry: status and prospectsOct 12 2007The experimental determination of the muon magnetic moment and its theoretical prediction within the Standard Model and the MSSM are reviewed. A 3 sigma deviation between experiment and Standard Model prediction has been established, and supersymmetry ... More

On causally asymmetric versions of Occam's Razor and their relation to thermodynamicsAug 24 2007Jan 30 2009In real-life statistical data, it seems that conditional probabilities for the effect given their causes tend to be less complex and smoother than conditionals for causes, given their effects. We have recently proposed and tested methods for causal inference ... More

On the entropy production of time series with unidirectional linearityAug 13 2009There are non-Gaussian time series that admit a causal linear autoregressive moving average (ARMA) model when regressing the future on the past, but not when regressing the past on the future. The reason is that, in the latter case, the regression residuals ... More

Non-Autonomous Maximal Regularity for Forms of Bounded VariationJun 11 2014Jun 12 2014We consider a non-autonomous evolutionary problem \[ u' (t)+\mathcal A (t)u(t)=f(t), \quad u(0)=u_0, \] where $V, H$ are Hilbert spaces such that $V$ is continuously and densely embedded in $H$ and the operator $\mathcal A (t)\colon V\to V^\prime$ is ... More

Equivariant $Γ$-spacesApr 30 2014The aim of this note is to provide a comprehensive treatment of the homotopy theory of $\Gamma$-$G$-spaces for $G$ a finite group. We introduce two level and stable model structures on $\Gamma$-$G$-spaces and exhibit Quillen adjunctions to $G$-symmetric ... More

Infinitely presented C(6)-groups are SQ-universalNov 26 2014We prove that infinitely presented classical $C(6)$ small cancellation groups are SQ-universal. We extend the result to graphical $Gr_*(6)$-groups over free products. For every $p\in\mathbb{N}$, we construct uncountably many pairwise non-quasi-isometric ... More

Topological entropy and distributional chaos in hereditary shifts with applications to spacing shifts and beta shiftsNov 01 2011Jan 08 2012Positive topological entropy and distributional chaos are characterized for hereditary shifts. A hereditary shift has positive topological entropy if and only if it is DC2-chaotic (or equivalently, DC3-chaotic) if and only if it is not uniquely ergodic. ... More

On the Computational Power of Molecular Heat EnginesFeb 02 2005A heat engine is a machine which uses the temperature difference between a hot and a cold reservoir to extract work. Here both reservoirs are quantum systems and a heat engine is described by a unitary transformation which decreases the average energy ... More

Quantum algorithm for measuring the energy of n qubits with unknown pair-interactionsAug 10 2001The well-known algorithm for quantum phase estimation requires that the considered unitary is available as a conditional transformation depending on the quantum state of an ancilla register. We present an algorithm converting an unknown n-qubit pair-interaction ... More

Satisfiability of Almost Disjoint CNF FormulasJul 08 2008Jul 10 2008We call a CNF formula linear if any two clauses have at most one variable in common. Let m(k) be the largest integer m such that any linear k-CNF formula with <= m clauses is satisfiable. We show that 4^k / (4e^2k^3) <= m(k) < ln(2) k^4 4^k. More generally, ... More

Using a Skewed Hamming Distance to Speed Up Deterministic Local SearchMay 26 2010Schoening presents a simple randomized algorithm for (d,k)-CSP problems with running time (d(k-1)/k)^n poly(n). Here, d is the number of colors, k is the size of the constraints, and n is the number of variables. A derandomized version of this, given ... More

Single-Peakedness and Total Unimodularity: Efficiently Solve Voting Problems Without Even TryingSep 12 2016Many NP-hard winner determination problems admit polynomial-time algorithms when restricting inputs to be single-peaked. Commonly, such algorithms employ dynamic programming along the underlying axis. We introduce a new technique: carefully chosen integer ... More

The Zak transform on strongly proper $G$-spaces and its applicationsMay 17 2016Oct 21 2016The Zak transform on $\mathbb{R}^d$ is an important tool in condensed matter physics, signal processing, time-frequency analysis, and harmonic analysis in general. This article introduces a generalization of the Zak transform to a class of locally compact ... More

How many phases meet at the chiral critical point?Feb 10 2009Aug 25 2009We explore the phase diagram of NJL-type models near the chiral critical point allowing for phases with spatially inhomogeneous chiral condensates. In the chiral limit it turns out that the region in the mean-field phase diagram where those phases are ... More

Automorphism Supergroups Of SupermanifoldsApr 10 2015A classical theorem states that the group of automorphisms of a manifold $M$ preserving a $G$-structure of finite type is a Lie group. We generalize this statement to the category of $cs$ manifolds and give some examples, some of which being generalizations ... More

Groups with graphical C(6) and C(7) small cancellation presentationsSep 30 2012Jul 24 2014We extend fundamental results of small cancellation theory to groups whose presentations satisfy the generalizations of the classical C(6) and C(7) conditions in graphical small cancellation theory. Using these graphical small cancellation conditions, ... More

Parameter degeneracies and (un)predictability of gravitational microlensing eventsNov 25 2008(abridged) Some difficulties in determining the physical properties that lead to observed anomalies in microlensing light curves, such as the mass and separation of extra-solar planets orbiting the lens star, or the relative source-lens parallax, are ... More

Theory and practice of microlensing lightcurves around fold singularitiesSep 22 2003Jun 23 2004Among all galactic microlensing events, those involving a passage of the observed source star over the caustic created by a binary lens are particularly useful in providing information about stellar atmospheres, the dynamics of stellar populations in ... More

A robust and efficient method for calculating the magnification of extended sources caused by gravitational lensesApr 06 1998To determine the magnification of an extended source caused by gravitational lensing one has to perform a two-dimensional integral over point-source magnifications in general. Since the point-source magnification jumps to an infinite value on caustics, ... More

Galactic microlensing with rotating binariesFeb 04 1997Sep 09 1997The influence of rotating binary systems on the light curves of galactic microlensing events is studied. Three different rotating binary systems are discussed: a rotating binary lens, a rotating binary source, and the motion of the earth around the sun ... More

A Lensing View On The Fundamental PlaneAug 05 2009For lensing galaxies we introduce a formal velocity dispersion sigma_lens, based on enclosed mass and the virial theorem. This is calculated from an ensemble of pixelated lens models, and found to be fairly model independent. A sample of 18 well-known ... More

Recognising Multidimensional Euclidean PreferencesFeb 25 2016Euclidean preferences are a widely studied preference model, in which decision makers and alternatives are embedded in d-dimensional Euclidean space. Decision makers prefer those alternatives closer to them. This model, also known as multidimensional ... More

$Σ_2^p$-complete Problems on Hedonic GamesSep 08 2015Hedonic games provide a general model of coalition formation, in which a set of agents is partitioned into coalitions, with each agent having preferences over which other players are in her coalition. We prove that with additively separable preferences, ... More

Inhomogeneous phases in the Nambu-Jona-Lasino and quark-meson modelJun 29 2009We discuss inhomogeneous ground states of the Nambu-Jona-Lasino (NJL) and quark-meson (QM) model within mean-field approximation and their possible existence in the respective phase diagrams. For this purpose we focus on lower dimensional modulations ... More

Unsatisfiable Linear k-CNFs Exist, for every kAug 17 2007We call a CNF formula linear if any two clauses have at most one variable in common. Let Linear k-SAT be the problem of deciding whether a given linear k-CNF formula is satisfiable. Here, a k-CNF formula is a CNF formula in which every clause has size ... More

PPZ For More Than Two Truth Values - An Algorithm for Constraint Satisfaction ProblemsOct 27 2010We analyze the so-called ppz algorithm for (d,k)-CSP problems for general values of d (number of values a variable can take) and k (number of literals per constraint). To analyze its success probability, we prove a correlation inequality for submodular ... More

Is there a physically universal cellular automaton or Hamiltonian?Sep 09 2010It is known that both quantum and classical cellular automata (CA) exist that are computationally universal in the sense that they can simulate, after appropriate initialization, any quantum or classical computation, respectively. Here we introduce a ... More

Trends in storm surge probability of occurrence along the Polish Baltic Sea coastOct 09 2014When assessing the hazard brought by storm surges on the coast, a frequency analysis is often conducted. An issue of particular concern is the sea level rise (SLR), thought to have an impact on maximum water levels. In this study, three gauge stations ... More

Non-Autonomous Forms and InvarianceSep 13 2016We generalize the Beurling--Deny--Ouhabaz criterion for parabolic evolution equations governed by forms to the non-autonomous, non-homogeneous and semilinear case. Let $V, H$ are Hilbert spaces such that $V$ is continuously and densely embedded in $H$ ... More

Search for single-top production with the ZEUS detector at HERAAug 23 2003A search for anomalous single-top production, ep -> etX, t -> Wb, has been made with the ZEUS detector at HERA using an integrated luminosity of 130 pb^-1. No evidence for top-quark production was found in either the leptonic or the hadronic decay channel ... More

Revealing stellar brightness profiles by means of microlensing fold causticsFeb 24 2004Jun 23 2004With a handful of measurements of limb-darkening coefficients, galactic microlensing has already proven to be a powerful technique for studying atmospheres of distant stars. Survey campaigns such as OGLE-III are capable of providing ~ 10 suitable target ... More

Determining the abundance of extragalactic planetsSep 23 2003Oct 23 2003Gravitational microlensing provides a unique technique to reveal information about extragalactic planets. A network of at least four 2m-class telescopes distributed around the northern hemisphere could probe 15-35 jupiters and 4-10 saturns around M31 ... More

The binary gravitational lens and its extreme casesMar 01 1999Sep 10 1999The transition of the binary gravitational lens from the equal mass case to small (planetary) mass ratios q is studied. It is shown how the limit of a (pure shear) Chang-Refsdal lens is approached, under what conditions the Chang-Refsdal approximation ... More

Corrections of Order $αα_s$ to W Boson DecaysJul 26 2013Nov 30 2015We present the calculation of the mixed two-loop QCD/electroweak corrections to hadronic W boson decays within the Standard Model. The optical theorem is applied to the W boson two-point function. The multi-scale integrals are computed with the help of ... More

Spin-1/2 particles moving on a 2D lattice with nearest-neighbor interactions can realize an autonomous quantum computerJun 30 2005Dec 12 2006What is the simplest Hamiltonian which can implement quantum computation without requiring any control operations during the computation process? In a previous paper we have constructed a 10-local finite-range interaction among qubits on a 2D lattice ... More

The non-existence of sharply $2$-transitive sets of permutations in $\mathrm{Sp}(2d,2)$ of degree $2^{2d-1} \pm 2^{d-1}$Feb 16 2016We use M\"uller and Nagy's method of contradicting subsets to give a new proof for the non-existence of sharply $2$-transitive subsets of the symplectic groups $\mathrm{Sp}(2d,2)$ in their doubly-transitive actions of degrees $2^{2d-1}\pm 2^{d-1}$. The ... More

Strangeness Photoproduction on Quasifree NeutronsOct 06 2015Strangeness photoproduction in the elementary reactions $\gamma N\rightarrow KY$ offers the possibility to study nucleon resonances in the mass region above 1.7 GeV, where the number of states and their properties are still under debate. These reactions ... More

Pseudodifferentialoperatoren mit nichtglatten Koeffizienten auf MannigfaltigkeitenNov 07 2013A generalization of differential operators are pseudodifferential operators which are used for reasoning about partial differential equations with variable coefficients. A lot of useful properties about classical pseudodifferential operators are already ... More

Optimal Scheduling for Linear-Rate Multi-Mode SystemsFeb 18 2013Linear-Rate Multi-Mode Systems is a model that can be seen both as a subclass of switched linear systems with imposed global safety constraints and as hybrid automata with no guards on transitions. We study the existence and design of a controller for ... More

Particle number conservation in quantum many-body simulations with matrix product operatorsApr 08 2011Oct 06 2011Incorporating conservation laws explicitly into matrix product states (MPS) has proven to make numerical simulations of quantum many-body systems much less resources consuming. We will discuss here, to what extent this concept can be used in simulation ... More

Can microlensing fold caustics reveal a second stellar limb-darkening coefficient?Mar 09 2004May 17 2004Dense high-precision photometry of microlensed stars during a fold-caustic passage can be used to reveal their intensity profiles from which the temperature of the stellar atmosphere as function of fractional radius can be derived. While the capabilities ... More

Effective potential for Polyakov loops from a center symmetric effective theory in three dimensionsNov 20 2009Jul 04 2012We present lattice simulations of a center symmetric dimensionally reduced effective field theory for SU(2) Yang Mills which employ thermal Wilson lines and three-dimensional magnetic fields as fundamental degrees of freedom. The action is composed of ... More

The Zak transform on strongly proper $G$-spaces and its applicationsMay 17 2016The Zak transform on $\mathbb{R}^d$ is an important tool in condensed matter physics, signal processing, time-frequency analysis, and harmonic analysis in general. This article introduces a generalization of the Zak transform to a class of locally compact ... More

Quantum thermodynamics with missing reference frames: Decompositions of free energy into non-increasing componentsNov 30 2005If an absolute reference frame with respect to time, position, or orientation is missing one can only implement quantum operations which are covariant with respect to the corresponding unitary symmetry group G. Extending observations of Vaccaro et al., ... More

Some Considerations on the Additional Absorption Peak in the c-axis Conductivity of Bilayer Cuprate Superconductors: Interpretation of the Changes Induced by a Parallel Magnetic Field and the Role of Bilayer SplittingAug 02 2004Changes of the 400 cm^{-1} peak in the c-axis conductivity of underdoped YBa2Cu3O6.6 upon application of a parallel magnetic field reported by Kojima et al. are shown to be consistent with the model where the peak is due to the superfluid. Results of ... More

Note on a Conjecture of WegnerJan 10 2008Jun 13 2011The optimal packings of n unit discs in the plane are known for those natural numbers n, which satisfy certain number theoretic conditions. Their geometric realizations are the extremal Groemer packings (or Wegner packings). But an extremal Groemer packing ... More

Gaussian quantum metrology and space-time probesOct 11 2016In this thesis we focus on Gaussian quantum metrology in the phase-space formalism and its applications in quantum sensing and the estimation of space-time parameters. We derive new formulae for the optimal estimation of multiple parameters encoded into ... More

Where are the binary source galactic microlensing events?Jan 13 1998Though there have been some galactic microlensing events which show a clear signature of a binary lens, no event has yet been claimed as due to lensing of a binary source. Here I argue that this may be due to the fact that most of the binary source events ... More

Estimating physical quantities for an observed galactic microlensing eventJan 08 1997Nov 13 1997For a given spatial distribution of the lenses and distribution of the transverse velocity of the lens relative to the line-of-sight, a probability distribution for the lens mass for a single observed event is derived. In addition, similar probability ... More

Uncovering galactic and extragalactic planets by gravitational microlensingDec 08 2003With its planet detection efficiency reaching a maximum for orbital radii between 1 and 10 AU, microlensing provides a unique sensitivity to planetary systems similar to our own around galactic and even extragalactic stars acting as lenses on observed ... More

Ambiguities in fits of binary lens galactic microlensing eventsFeb 28 1997Aug 13 1998For observed galactic microlensing events only one fit is usually presented, though, especially for a binary lens, several fits may be possible. This has been shown for the MACHO LMC#1 event (Dominik & Hirshfeld 1996). Here I discuss the strong binary ... More

Abelian varieties with quaternion and complex multiplicationAug 28 2012In this paper we study abelian varieties which correspond to CM points in the coarse moduli space of principally polarized abelian varieties with multiplication by a maximal order in a quaternion algebra over a totally real number field. These are abelian ... More

Mean curvature flow with obstacles: a viscosity approachSep 26 2014Oct 21 2016We introduce a level-set formulation for the mean curvature flow with obstacles and show existence and uniqueness of a viscosity solution. These results generalize a well known viscosity approach for the mean curvature flow without obstacle by Evans and ... More

A Bose-Einstein condensate bouncing off a rough mirrorSep 28 2005We present experimental results and theoretical analysis of the diffuse reflection of a Bose-Einstein condensate from a rough mirror. The mirror is produced by a blue-detuned evanescent wave supported by a dielectric substrate. The results are carefully ... More

Elements related to the largest complete excursion of a reflected BM stopped at a fixed time. Application to local scoreJun 19 2014Elements related to the largest complete excursion of a reflected BM stopped at a fixed time. Application to local score.

Dynamic Erdös- Rényi random graph with forbidden degreeFeb 26 2016As suggested by Itai Benjamini, we introduced a variant of the Erd\"os- R\'enyi random graph process with a forbidden degree $k$, in which every edge adjacent to a vertex $v$ is removed when the degree of $v$ reaches $k$ (but the removed edges may very ... More

Conservation laws in the modeling of moving crowdsNov 02 2012This paper is a proceeding of the conference hyp2012 that was held in Padova in June 2012. Models for crowd dynamics are presented and compared. Well posedness results allow to exhibit the existence of optimal controls in various situations. A new approach ... More

A Class of Non-Local Models for Pedestrian TrafficApr 15 2011Apr 20 2011We present a new class of macroscopic models for pedestrian flows. Each individual is assumed to move towards a fixed target, deviating from the best path according to the instantaneous crowd distribution. The resulting equation is a conservation law ... More

Continuity results for TV-minimizersMay 31 2016This paper deals with continuity preservation when minimizing generalized total variation with a $L^2$ fidelity term or a Dirichlet boundary condition. We extend several recent results in the two cases, mainly by showing comparison principles for the ... More

A novel internal waves generatorSep 29 2006We present a new kind of generator of internal waves which has been designed for three purposes. First, the oscillating boundary conditions force the fluid particles to travel in the preferred direction of the wave ray, hence reducing the mixing due to ... More

Global smooth solutions of Euler equations for Van der Waals gasesMar 25 2010We prove global in time existence of solutions of the Euler compressible equations for a Van der Waals gas when the density is small enough in $\H{m}$, for $m$ large enough. To do so, we introduce a specific symmetrisation allowing areas of null density. ... More

Conjugacy growth series of some wreath productsOct 25 2016In this paper we consider groups of the form $G\wr L$, where the set of generators naturally extends the sets of generators of $G$ and $L$, and $L$ admits a Cayley graph that is a tree. We show how one can compute the conjugacy growth series of such groups ... More

Estimating diagonal entries of powers of sparse symmetric matrices is BQP-completeJun 27 2006Oct 20 2006Let A be a real symmetric matrix of size N such that the number of the non-zero entries in each row is polylogarithmic in N and the positions and the values of these entries are specified by an efficiently computable function. We consider the problem ... More

Fluctuations of Functions of Wigner MatricesOct 22 2016We show that matrix elements of functions of $N\times N$ Wigner matrices fluctuate on a scale of order $N^{-1/2}$ and we identify the limiting fluctuation. Our result holds for any function $f$ of the matrix that satisfies $\int (1+|\xi|)\lvert\widehat ... More

Phonon anomalies in trilayer high-Tc superconductorsDec 09 2003We present an extension of the model proposed recently to account for dramatic changes below Tc (anomalies) of some c-axis polarized infrared-active phonons in bilayer cuprate superconductors, that applies to trilayer high-Tc compounds. We discuss several ... More

Formal power seriesApr 19 1994In this article we will describe the \Maple\ implementation of an algorithm presented in~\cite{Koe92}--\cite{Koeortho} which computes an {\em exact\/} formal power series (FPS) of a given function. This procedure will enable the user to reproduce most ... More

Fragility of a class of highly entangled states of many quantum-bitsJul 10 1999We consider a Quantum Computer with n quantum-bits (`qubits'), where each qubit is coupled independently to an environment affecting the state in a dephasing or depolarizing way. For mixed states we suggest a quantification for the property of showing ... More

Distinguishing n Hamiltonians on C^n by a single measurementMar 06 2001If an experimentalist wants to decide which one of n possible Hamiltonians acting on an n dimensional Hilbert space is present, he can conjugate the time evolution by an appropriate sequence of known unitary transformations in such a way that the different ... More

Remark on multi-particle observables and entangled states with constant complexityMar 24 2000We show that every density matrix of an n-particle system prepared by a quantum network of constant depth is asymptotically commuting with the mean-field observables. We introduce certain pairs of hypersurfaces in the space of density matrices and give ... More

Unsatisfiable CNF Formulas need many ConflictsJun 06 2008Sep 06 2010A pair of clauses in a CNF formula constitutes a conflict if there is a variable that occurs positively in one clause and negatively in the other. A CNF formula without any conflicts is satisfiable. The Lovasz Local Lemma implies that a k-CNF formula ... More

Violation of the Holographic Viscosity Bound in a Strongly Coupled Anisotropic PlasmaOct 31 2011Dec 08 2011We study the conductivity and shear viscosity tensors of a strongly coupled N=4 super-Yang-Mills plasma which is kept anisotropic by a theta parameter that depends linearly on one of the spatial dimensions. Its holographic dual is given by an anisotropic ... More

Optimal probe states for the estimation of Gaussian unitary channelsMar 17 2016We construct a practical method for finding optimal Gaussian probe states for the estimation of parameters encoded by Gaussian unitary channels. This method can be used for finding all optimal probe states, rather than focussing on the performance of ... More

Importance Sampling for MinibatchesFeb 06 2016Minibatching is a very well studied and highly popular technique in supervised learning, used by practitioners due to its ability to accelerate training through better utilization of parallel processing power and reduction of stochastic variance. Another ... More

Dynamics of pair correlations in the attractive Lieb-Liniger gasJun 28 2010We investigate the dynamics of a 1D Bose gas after a quench from the Tonks-Girardeau regime to the regime of strong attractive interactions applying analytical techniques and exact numerical simulations. After the quench the system is found to be predominantly ... More

Gauge dependence and renormalization of tan(beta)Oct 28 2002Renormalization schemes for tan(beta) are discussed in view of their gauge dependence. It is shown that several common renormalization schemes lead to a gauge-dependent definition of tan(beta), whereas two classes of gauge-independent schemes show even ... More

Gauge dependence and renormalization of $\tanβ$ in the MSSMMay 24 2002May 24 2004Well-known and newly developed renormalization schemes for $\tan\beta$ are analyzed in view of three desirable properties: gauge independence, process independence, and numerical stability in perturbation theory. Arguments are provided that no scheme ... More

Quantum mechanical picture of the coupling between interlayer electronic excitations and infrared active phonons in bilayer cuprate superconductorsMar 29 2012The formula frequently used to describe the c-axis infrared response of the coupled electron-phonon system of bilayer cuprate superconductors and providing important insights into the physics of these materials has been originally obtained at the level ... More

Fluctuations of Rectangular Young Diagrams of Interlacing Wigner EigenvaluesAug 18 2016Sep 14 2016We prove a new CLT for the difference of linear eigenvalue statistics of a Wigner random matrix $H$ and its minor $\hat H$ and find that the fluctuation is much smaller than the fluctuations of the individual linear statistics, as a consequence of the ... More

Observing Each Other's Observations in the Electronic Mail GameDec 19 2014We study a Bayesian coordination game where agents receive private information on the game's payoff structure. In addition, agents receive private signals on each other's private information. We show that once agents possess these different types of information, ... More

H_2D^+: a light on baryonic dark matter?Feb 27 2006It has been suggested that the dark halos of galaxies are constituted by cloudlets of cold (< 10 K) H_2 and dense (> 10^7$ cm^{-3}) molecular gas. Such gas is extremely difficult to detect, because the classical tracers of molecular gas, CO and/or dust ... More

The influence of grain rotation on the structure of dust aggregatesJan 12 2006Jan 13 2006We study the effect of rotation during the collision between dust aggregates, in order to address a mismatch between previous model calculations of Brownian motion driven aggregation and experiments. We show that rotation during the collision does influence ... More

An Explicit Polynomial with Higman-Sims Group as Galois Group over Q(t)Nov 14 2016We compute explicit polynomials having the sporadic Higman-Sims group HS and its automorphism group Aut(HS) as Galois groups over the rational function field Q(t).

Stirring up the dust: A dynamical model for halo-like dust clouds in transitional disksMay 26 2011A small number of young stellar objects show signs of a halo-like structure of optically thin dust. This halo or torus is located within a few AU of the star, but its origin has not yet been understood. A dynamically excited cloud of planetesimals colliding ... More

The structure of dust aggregates in hierarchical coagulationNov 01 2016Dust coagulation in interstellar space and protoplanetary disks is usually treated as one of 2 extreme cases: Particle-Cluster Aggregation and Cluster-Cluster Aggregation. In this paper we study the process of hierarchical growth, where aggregates are ... More

Dimensional Reduction and Hadronic ProcessesSep 12 2008We consider the application of regularization by dimensional reduction to NLO corrections of hadronic processes. The general collinear singularity structure is discussed, the origin of the regularization-scheme dependence is identified and transition ... More

Decision Problems for Nash Equilibria in Stochastic GamesApr 21 2009Jun 08 2009We analyse the computational complexity of finding Nash equilibria in stochastic multiplayer games with $\omega$-regular objectives. While the existence of an equilibrium whose payoff falls into a certain interval may be undecidable, we single out several ... More

The Complexity of Nash Equilibria in Simple Stochastic Multiplayer GamesFeb 02 2009Apr 10 2009We analyse the computational complexity of finding Nash equilibria in simple stochastic multiplayer games. We show that restricting the search space to equilibria whose payoffs fall into a certain interval may lead to undecidability. In particular, we ... More

Probing Two Holographic Models of Strongly Coupled Anisotropic PlasmaMay 21 2012Jul 27 2012Quark-gluon plasma during its initial phase after its production in heavy-ion collisions is expected to have substantial pressure anisotropies. In order to model this situation by a strongly coupled N=4 super-Yang-Mills plasma with fixed anisotropy by ... More

Electromagnetic signatures of a strongly coupled anisotropic plasmaJun 17 2011Aug 29 2011In heavy-ion collisions, quark-gluon plasma is likely to be produced with sizable initial pressure anisotropy, which may leave an imprint on electromagnetic observables. In order to model a strongly coupled anisotropic plasma, we use the AdS/CFT correspondence ... More

Bounds on the entropy generated when timing information is extracted from microscopic systemsJan 23 2003We consider Hamiltonian quantum systems with energy bandwidth \Delta E and show that each measurement that determines the time up to an error \Delta t generates at least the entropy (\hbar/(\Delta t \Delta E))^2/2. Our result describes quantitatively ... More

Are there quantum bounds on the recyclability of clock signals in low power computers?Feb 11 2002Even if a logical network consists of thermodynamically reversible gate operations, the computation process may have high dissipation rate if the gate implementation is controlled by external clock signals. It is an open question whether the global clocking ... More

Simple Causes of Complexity in Hedonic GamesJul 13 2015Hedonic games provide a natural model of coalition formation among self-interested agents. The associated problem of finding stable outcomes in such games has been extensively studied. In this paper, we identify simple conditions on expressivity of hedonic ... More

The Influence of Frequency, Recency and Semantic Context on the Reuse of Tags in Social Tagging SystemsApr 04 2016In this paper, we study factors that influence tag reuse behavior in social tagging systems. Our work is guided by the activation equation of the cognitive model ACT-R, which states that the usefulness of information in human memory depends on the three ... More

Infinitely presented graphical small cancellation groups are acylindrically hyperbolicAug 19 2014Feb 09 2016We prove that infinitely presented graphical $Gr(7)$ small cancellation groups are acylindrically hyperbolic. In particular, infinitely presented classical $C(7)$-groups and, hence, classical $C'(\frac{1}{6})$-groups are acylindrically hyperbolic. We ... More