Searching Arxiv, refresh for possibly better results.

total 418took 0.10s

Learning Gaussian Graphical Models by symmetric parallel regression techniqueFeb 08 2019In this contribution we deal with the problem of learning an undirected graph which encodes the conditional dependence relationship between variables of a complex system, given a set of observations of this system. This is a very central problem of modern ... More

Percolation of New Product Critical Market PenetrationApr 04 2004A simulation of new product market penetration in a social environment is performed, using a spintronic model, where each element of a 3D network interacts with its first neighbors. Agents are assumed to be rational, with a perfect market foresight. Unitary ... More

Anomalous CMB north-south asymmetrySep 05 2008Several accurate analyses have revealed a statistically significant North-South ecliptic asymmetry in the large-angle correlations strength of the Cosmic Microwave Background (CMB) radiation temperature field data from the Wilkinson Microwave Anisotropy ... More

Predicting online user behaviour using deep learning algorithmsNov 19 2015May 26 2016We propose a robust classifier to predict buying intentions based on user behaviour within a large e-commerce website. In this work we compare traditional machine learning techniques with the most advanced deep learning approaches. We show that both Deep ... More

A new macroscopic model derived from the Boltzmann equation and the discontinuous Galerkin method for solving kinetic equationsSep 05 2011We propose a new macroscopic model derived from the classical nonlinear Boltzmann equation. A set of partial differential equations is obtained easily. The unknowns depend on the time and space coordinates, and are related to the distribution function, ... More

A semi-discrete Boltzmann equation based on a finite volume schemeNov 28 2017In this work we consider the classical non-linear Boltzmann equation, where the unknown is the distribution function $f$, which depends on the time $t$, the vector $\mathbf{x}$ (the position of a molecule) and its velocity $\mathbf{\xi}$. From the Boltzmann ... More

Stationary solutions to a Vlasov equation for planetary ringsDec 02 2013In this paper we consider a Vlasov or collisionless Boltzmann equation describing the dynamics of planetary rings. We propose a simple physical model, where the particles of the rings move under the gravitational Newtonian potential of two primary bodies. ... More

Is the cold spot responsible for the CMB North-South asymmetry?Dec 06 2009Several intriguing phenomena, unlikely within the standard inflationary cosmology, were reported in the cosmic microwave background (CMB) data from WMAP and appear to be uncorrelated. Two of these phenomena, termed CMB anomalies, are representative of ... More

The large-scale angular correlations in CMB temperature mapsNov 19 2005Observations show that the Cosmic Microwave Background (CMB) contains tiny variations at the 10^{-5} level around its black-body equilibrium temperature. The detection of these temperature fluctuations provides to modern Cosmology evidence for the existence ... More

Non-linear evolution equations and hyperelliptic covers of elliptic curvesMar 01 2010We study the general properties of spectral curves associated to doubly-periodic solutions of Korteweg-deVries, sine-Gordon, Non-linear Schr\"odinger and 1D Toda equations, and construct examples of arbitrary genus.

The Ergodic Closing Lemma for Nonsingular EndomorphismsJun 11 2009Jun 15 2009We prove the ergodic Closing Lemma for Nonsingular Endomorphisms.

New Criteria of Generic Hyperbolicity based on Periodic PointsJun 12 2009Jun 12 2012We prove a criteria for uniform hyperbolicity based on the periodic points of the transformation. More precisely, if a mild (non uniform) hyperbolicity condition holds for the periodic points of any diffeomorphism in a residual subset of a $C^1$-open ... More

Maximal index automorphisms of free groups with no attracting fixed points on the boundary are Dehn twistsJan 16 2001Nov 12 2002In this paper we define a quantity called the rank of an outer automorphism of a free group which is the same as the index introduced in [D. Gaboriau, A. Jaeger, G. Levitt and M. Lustig, `An index for counting fixed points for automorphisms of free groups', ... More

Hyperelliptic $d$-osculating covers and rational surfacesNov 12 2010Let $\mathbb{P}^1$ and $(X,q)$ denote, respectively, the projective line and a fixed elliptic curve marked at its origin, both defined over an algebraically closed field $\mathbb{K}$ of arbitrary characteristic $\emph{\textbf{p}} \neq2$. We will consider ... More

Copernican Cosmography in the First Mexican Physics TreatiseNov 27 2004Copernican Cosmography was used to discover the path linking Cebu islands and Acapulco via Kuro-Shivo Stream, as registered in Physica Speculatio, first physics book written in New Spain. Teaching and practice of Copernican theory were an outcome of both ... More

A non-parametric and scale-independent method for cluster analysis II: the multivariate caseAug 31 1995A general method is described for detecting and analysing galaxy systems. The multivariate geometrical structure of the sample is studied by using an extension of the method which we introduced in a previous paper. The method is based on an estimate of ... More

Knowledge Representation in Graphs using Convolutional Neural NetworksDec 07 2016Knowledge Graphs (KG) constitute a flexible representation of complex relationships between entities particularly useful for biomedical data. These KG, however, are very sparse with many missing edges (facts) and the visualisation of the mesh of interactions ... More

A proof that all Seifert 3-manifold groups and all virtual surface groups are conjugacy separableMay 26 2005We prove that the fundamental group of any Seifert 3-manifold is conjugacy separable. That is, conjugates may be distinguished in finite quotients or, equivalently, conjugacy classes are closed in the pro-finite topology.

A Natural Concept of Image in the Physics of fr. Alonso de la VeracruzJan 01 2001Alonso de la Veracruz conducted a physical study of image, regarding the activities of Soul in which image is produced, as organic operations. This research was particularly important since, at that time, image was systematically used to propagate the ... More

A deterministic numerical model for the nonlinear Boltzmann equationNov 19 2010Aug 29 2011We propose a new deterministic numerical scheme, based on the discontinuous Galerkin method, for solving the Boltzamnn equation for rarefied gases. The new scheme guarantees the conservation of the mass, momentum and energy. We avoid any stochastic procedures ... More

A BGK model for charge transport in grapheneDec 05 2018The Boltzmann equation describes the detailed microscopic behaviour of a dilute gas, and represents the basis of the kinetic theory of gases. In order to reduce the difficulties in solving the Boltzmann equation, simple expressions of a collision operator ... More

Interbreeding conditions for explaining Neandertal DNA in living humans: the nonneutral caseMay 30 2011We consider here an extension of a previous work by Neves and Serva, still unpublished, which estimates the amount of interbreeding between anatomically modern Africans and Neandertals necessary for explaining the experimental fact that 1 to 4% of the ... More

Irreversible processes without energy dissipation in an isolated Lipkin-Meshkov-Glick modelApr 24 2014Sep 29 2015For a certain class of isolated quantum systems, we report the existence of irreversible processes in which the energy is not dissipated. After a closed cycle in which the initial energy distribution is fully recovered, the expectation value of a symmetry-breaking ... More

Statistical properties of the maximal entropy measure for partially hyperbolic attractorsOct 05 2016We show the existence and uniqueness of the maximal entropy probability measure for partially hyperbolic diffeomorphisms which are semi-conjugate to nonuniformly expanding maps. Using the theory of projective metric on cones we then prove exponential ... More

Skew Poincaré-Birkhoff-Witt extensions over weak $Σ$-rigid ringsMay 29 2018In this paper we introduce the notion of weak $\Sigma$-rigid ring which extends $\alpha$-rigid rings and $\Sigma$-rigid rings defined for Ore extensions and skew PBW extensions, respectively. We also present the notion of weak $\Sigma$-skew Armendariz ... More

Skew PBW extensions over weak symmetric and $(Σ,Δ)$-weak symmetric ringsJul 13 2018In this paper we study skew Poincar\'e-Birkhoff-Witt extensions over weak symmetric and $(\Sigma,\Delta)$-weak symmetry rings. Since these extensions generalize Ore extensions of injective type and another noncommutative rings of polynomial type, we unify ... More

A generalized Koszul property for skew PBW extensionsApr 18 2018Let R be a commutative algebra. In this paper we show that constant skew PBW extensions of a generalized Koszul algebra R are also generalized Koszul. Let A be a semi-commutative skew PBW extension of R such that A is R-augmented. We show also that if ... More

Automated Symbolic Analysis of ARBAC-Policies (Extended Version)Dec 27 2010One of the most widespread framework for the management of access-control policies is Administrative Role Based Access Control (ARBAC). Several automated analysis techniques have been proposed to help maintaining desirable security properties of ARBAC ... More

A method to search for topological signatures in the angular distribution of cosmic objectsNov 10 2005We present a method to search for large angular-scale correlations, termed topological signatures, in the angular distribution of cosmic objects, which does not depend on cosmological models or parameters and is based only on the angular coordinates of ... More

Revêtements hyperelliptiques d-osculateurs et solitons elliptiques de la hiérarchie KdVDec 04 2009Let $d$ be a positive integer, $\mathbb K$ an algebraically closed field of characteristic 0 and $ X$ an elliptic curve defined over K. We study the hyperelliptic curves equipped with a projection over $ X$, such that the natural image of $ X$ in the ... More

End-User Effects of Microreboots in Three-Tiered Internet SystemsMar 06 2004Microreboots restart fine-grained components of software systems "with a clean slate," and only take a fraction of the time needed for full system reboot. Microreboots provide an application-generic recovery technique for Internet services, which can ... More

Scaling properties of soft matter in equilibrium and under stationary flowDec 05 2016A brief review is presented of the scaling of complex fluids, polymers and polyelectrolytes in solution and in confined geometry, in thermodynamical, structural and rheology properties using equilibrium and nonequilibrium dissipative particle dynamics ... More

Second Order Multigrid Methods for Elliptic Problems with Discontinuous Coefficients on an Arbitrary Interface, I: One Dimensional ProblemsNov 04 2011In this paper we present a one dimensional second order accurate method to solve Elliptic equations with discontinuous coefficients on an arbitrary interface. Second order accuracy for the first derivative is obtained as well. The method is based on the ... More

On non-contractible periodic orbits for surface homeomorphismsJul 05 2013Oct 10 2014In this work we study homeomorphisms of closed orientable surfaces homotopic to the identity, focusing on the existence of non-contractible periodic orbits. We show that, if $g$ is such a homeomorphism, and if $\hat g$ is its lift to the universal covering ... More

Koszulity for skew PBW extensions over fieldsNov 11 2016Koszul and homogeneous Koszul algebras were defined by Priddy in \cite{Priddy1970}. There exist some relations between these algebras and the skew PBW extensions introduced in \cite{LezamaGallego}. In this paper we give conditions to guarantee that skew ... More

Bose-Einstein Condensation of Magnons in NiCl2-4SC(NH2)2May 31 2012A Bose-Einstein condensation (BEC) has been observed in magnetic insulators in the last decade. The bosons that condensed are magnons, associated with an ordered magnetic phase induced by a magnetic field. We review the experiments in the spin-gap compound ... More

Metric properties of Outer SpaceMar 05 2008Dec 17 2008We define metrics on Culler-Vogtmann space, which are an analogue of the Teichmuller metric and are constructed using stretching factors. In fact the metrics we study are related, one being a symmetrised version of the other. We investigate the basic ... More

Finite groups acting on coherent sheaves and Galois coversFeb 11 2003Let G be a finite group and \rho: G--> End(E) be a group representation of G on a coherent sheaf over an integral scheme. The purpose of this paper shall give a decomposition theorem of such representations in non-splitting components and apply this results ... More

Non-thermal quantum phase transitionsMay 14 2013We report a kind of quantum phase transition which takes place in isolated quantum systems with non-thermal equilibrium states and an extra symmetry that commutes with the Hamiltonian for any values of the system parameters. A critical energy separates ... More

Conjugacy in normal subgroups of hyperbolic groupsJun 08 2009Oct 11 2016Let N be a finitely generated normal subgroup of a Gromov hyperbolic group G. We establish criteria for N to have solvable conjugacy problem and be conjugacy separable in terms of the corresponding properties of G/N. We show that the hyperbolic group ... More

New Upper Bounds on the Distance Domination Numbers of GridsOct 15 2014In his 1992 Ph.D. thesis Chang identified an efficient way to dominate $m \times n$ grid graphs and conjectured that his construction gives the most efficient dominating sets for relatively large grids. In 2011 Gon\c{c}alves, Pinlou, Rao, and Thomass\'e ... More

Enveloping Algebra and Skew Calabi-Yau algebras over Skew Poincaré-Birkhoff-Witt ExtensionsApr 18 2018In this paper we show that the tensor product of skew PBW extensions is a skew PBW ex- tension. We also characterize the enveloping algebra of a skew PBW extension. Finally, we establish sufficient conditions to guarantee the property of being skew Calabi-Yau ... More

Linear response, and consequences for differentiability of statistical quantities and Multifractal AnalysisNov 16 2017Nov 28 2017In this article we initially fix ourselves to smooth expanding dynamical systems. We prove the differentiability of the topological pressure, equilibrium states and their densities with respect to smooth expanding dynamical systems and any smooth potential. ... More

The isometry group of Outer SpaceDec 01 2009We prove analogues of Royden's Theorem for the Lipschitz metrics of Outer Space, namely that Isom(CV_n) is Out(F_n).

Intersections of self-gravitating charged shells in a Reissner-Nordstrom fieldDec 12 2008Jan 26 2009We describe the equation of motion of two charged spherical shells with tangential pressure in the field of a central Reissner-Nordstrom (RN) source. We solve the problem of determining the motion of the two shells \textsl{after} the intersection by solving ... More

Equilibrium states for non-uniformly expanding maps: decay of correlations and strong stabilityMay 24 2012Jul 19 2012We study the rate of decay of correlations for equilibrium states associated to a robust class of non-uniformly expanding maps where no Markov assumption is required. We show that the Ruelle-Perron-Frobenius operator acting on the space of Holder continuous ... More

PBW bases for some 3-dimensional skew polynomial algebrasMay 09 2018The aim of this paper is to establish necessary and sufficient algorithmic conditions to guarantee that an algebra is actually a 3-dimensional skew polynomial algebra in the sense of Bell and Smith.

Engineering of quantum dot photon sources via electro-elastic fieldsMar 01 2015The possibility to generate and manipulate non-classical light using the tools of mature semiconductor technology carries great promise for the implementation of quantum communication science. This is indeed one of the main driving forces behind ongoing ... More

Primitive recursive functions versus partial recursive functions: comparing the degree of undecidabilityJul 06 2016Consider a decision problem whose instance is a function. Its degree of undecidability, measured by the corresponding class of the arithmetic (or Kleene-Mostowski) hierarchy hierarchy, may depend on whether the instance is a partial recursive or a primitive ... More

The Tracy-Widom distribution is not infinitely divisibleJan 12 2016The classical infinite divisibility of distributions related to eigenvalues of some random matrix ensembles is investigated. It is proved that the $\beta$-Tracy-Widom distribution, which is the limiting distribution of the largest eigenvalue of a $\beta$-Hermite ... More

Stretching factors, metrics and train tracks for free productsDec 15 2013Apr 20 2015In this paper we develop the metric theory for the outer space of a free product of groups. This generalizes the theory of the outer space of a free group, and includes its relative versions. The outer space of a free product is made of $G$-trees with ... More

Transitivity and rotation sets with nonempty interior for homeomorphisms of the 2-TorusDec 04 2010We show that, if $f$ is a homeomorphism of the 2--torus isotopic to the identity, and its lift $\widetilde f$ is transitive, or even if it is transitive outside of the lift of the elliptic islands, then $(0,0)$ is in the interior of the rotation set of ... More

Some homological properties of skew PBW extensionsOct 24 2013We prove that if R is a left Noetherian and left regular ring then the same is true for any bijective skew PBW extension A of R. From this we get Serre's Theorem for such extensions. We show that skew PBW extensions and its localizations include a wide ... More

A Finite Difference Ghost-Cell Multigrid Approach for Poisson Equation with Mixed Boundary Conditions in Arbitrary DomainNov 03 2011In this paper we present a multigrid approach to solve the Poisson equation in arbitrary domain (identified by a level set function) and mixed boundary conditions. The discretization is based on finite difference scheme and ghost-cell method. This multigrid ... More

$σ$-PBW Extensions of Skew Armendariz RingsNov 04 2016The aim of this paper is to investigate a general notion of $\sigma$-PBW extensions over Armendariz rings. As an application, the properties of being Baer, quasi-Baer, p.p. and p.q.-Baer are established for these extensions. We generalize several results ... More

Burchnall-Chaundy theory for skew Poincaré-Birkhoff-Witt extensionsMay 26 2018In this paper we review some classical results on the algebraic dependence of commuting elements in several noncommutative algebras as differential operator rings and Ore extensions. Then we extend all these results to a more general setting, the family ... More

On the stability of the positive mass theorem for asymptotically hyperbolic graphsMar 05 2018The positive mass theorem states that the total mass of a complete asymptotically flat manifold with non-negative scalar curvature is non-negative; moreover, the total mass equals zero if and only if the manifold is isometric to the Euclidean space. Huang ... More

Qualitative analysis of Kantowski-Sachs metric in a generic class of $f(R)$ modelsAug 27 2013May 26 2014In this paper we investigate, from the dynamical systems perspective, the evolution of a Kantowski-Sachs metric in a generic class of $f(R)$ models. We present conditions (i. e., differentiability conditions, existence of minima, monotony intervals, etc.) ... More

Global Stability properties for a class of dissipative phenomena via one or several Liapunov functionalsNov 07 2003We find some new results regarding the existence, uniqueness, boundedness, stability and attractivity of the solutions of a class of initial-boundary-value problems characterized by a quasi-linear third order equation which may have non-autonomous forcing ... More

On the Nature of $a^{*}_{k}a_{k}$ and the Emergence of the Born's RuleSep 08 2010Jun 01 2012This paper is intended to show that a review in the concept of the game theoretical utility, the revised utility to be applied to the definition of the utility of a wave function representing an object subsystem relative to its observer subsystem, both ... More

Stability and attractivity for a class of dissipative phenomenaMar 06 2001We consider initial-boundary-value problems for a class of nonlinear third order equations having non-autonomous forcing terms and get new asymptotic stability results by means of the Liapunov second method. The class includes equations arising in Superconductor ... More

Existence, uniqueness and stability for a class of third order dissipative problems depending on timeOct 25 2012We prove new results regarding the existence, uniqueness, (eventual) boundedness, (total) stability and attractivity of the solutions of a class of initial-boundary-value problems characterized by a quasi-linear third order equation which may contain ... More

Unveiling a crystalline topological insulator in a Weyl semimetal with time-reversal symmetryJun 17 2014We consider a natural generalization of the lattice model for a periodic array of two layers, A and B, of spinless electrons proposed by Fu [Phys. Rev. Lett. 106, 106802 (2011)] as a prototype for a crystalline insulator. This model has time-reversal ... More

Fully essential dynamics for area-preserving surface homeomorphismsJul 16 2015Jun 04 2016We study the interplay between the dynamics of area-preserving surface homeomorphisms homotopic to the identity and the topology of the surface. We define fully essential dynamics and generalize the results previously obtained on strictly toral dynamics ... More

Relativistically speaking: Let's walk or run through the rain?Nov 27 2010Dec 02 2010We analyse under a simple approach the problem one must decide the best strategy to minimize the contact with rain when moving between two points through the rain. The available strategies: walk (low speed boost $<<$ $c$) or run (relativistic speed boost ... More

Strictly Toral DynamicsJan 05 2012May 22 2013This article deals with nonwandering (e.g. area-preserving) homeomorphisms of the torus $\mathbb{T}^2$ which are homotopic to the identity and strictly toral, in the sense that they exhibit dynamical properties that are not present in homeomorphisms of ... More

A conditional compression distance that unveils insights of the genomic evolutionJan 16 2014We describe a compression-based distance for genomic sequences. Instead of using the usual conjoint information content, as in the classical Normalized Compression Distance (NCD), it uses the conditional information content. To compute this Normalized ... More

A HIC Primitive Spinodal Decomposition SignatureMar 29 2005Mar 29 2005Evidence of a primitive spinodal decomposition has been obtained for central Ni+Ni Heavy Ion Collision, since higher order charge correlations show a peak when four fragments of size equal to 6 are produced with an excitation of 4.75 MeV. This can be ... More

Qualitative properties for a class of non-autonomous semi-linear 3rd order PDE arising in dissipative problemsJan 13 2010We improve results regarding the stability and attractivity of solutions $u$ of a large class of initial-boundary-value problems characterized by a semi-linear third order equation which may contain time-dependent coefficients. In the proof we use Liapunov ... More

Cheap Recovery: A Key to Self-Managing StateJun 23 2004Cluster hash tables (CHTs) are a key persistent-storage component of many large-scale Internet services due to their high performance and scalability. We show that a correctly-designed CHT can also be as easy to manage as a farm of stateless servers. ... More

Bounded and unbounded behavior for area-preserving rational pseudo-rotationsJul 24 2012Apr 19 2014A rational pseudo-rotation $f$ of the torus is a homeomorphism homotopic to the identity with a rotation set consisting of a single vector $v$ of rational coordinates. We give a classification for rational pseudo-rotations with an invariant measure of ... More

Automatic Generation of Formula Simplifiers based on Conditional Rewrite RulesFeb 23 2016This paper addresses the problem of creating simplifiers for logic formulas based on conditional term rewriting. In particular, the paper focuses on a program synthesis application where formula simplifications have been shown to have a significant impact. ... More

Stability properties for some non-autonomous dissipative phenomena proved by families of Liapunov functionalsJul 31 2008We prove some new results regarding the boundedness, stability and attractivity of the solutions of a class of initial-boundary-value problems characterized by a quasi-linear third order equation which may contain time-dependent coefficients. The class ... More

Proceedings Second Workshop on SynthesisMar 28 2014Software synthesis is rapidly developing into an important research area with vast potential for practical application. The SYNT Workshop on Synthesis aims to bringing together researchers interested in synthesis to present both ongoing and mature work ... More

Area-preserving irrotational diffeomorphisms of the torus with sublinear diffusionJun 11 2012We construct a $C^\infty$ area-preserving diffeomorphism of the two-dimensional torus which is Bernoulli (in particular, ergodic) with respect to Lebesgue measure, homotopic to the identity, and has a lift to the universal covering whose rotation set ... More

Graph-wreath products and finiteness conditionsJul 01 2014Aug 02 2015A notion of \emph{graph-wreath product} is introduced. We obtain sufficient conditions for these products to satisfy the topologically inspired finiteness condition type $\operatorname{F}_n$. Under various additional assumptions we show that these conditions ... More

Quantum Walks as simulators of neutrino oscillations in vacuum and matterJul 02 2016Sep 08 2016We analyze the simulation of Dirac neutrino oscillations using quantum walks, both in vacuum and in matter. We show that this simulation, in the continuum limit, reproduces a set of coupled Dirac equations that describe neutrino flavor oscillations, and ... More

Scaling law of the disjoining pressure reveals two dimensional structure of polymeric fluidsMar 09 2015A scaling relation for the disjoining pressure of strongly confined polymer fluids is proposed for the first time, which yields directly the scaling exponent, nu, of the radius of gyration for polymers. To test the proposed scaling relation we performed ... More

Fully essential dynamics for area-preserving surface homeomorphismsJul 16 2015Nov 17 2016We study the interplay between the dynamics of area-preserving surface homeomorphisms homotopic to the identity and the topology of the surface. We define fully essential dynamics and generalize the results previously obtained on strictly toral dynamics ... More

Kurosh rank of intersections of subgroups of free products of orderable groupsSep 01 2011Jan 21 2014We prove that the reduced Kurosh rank of the intersection of two subgroups $H$ and $K$ of a free product of right-orderable groups is bounded above by the product of the reduced Kurosh ranks of $H$ and $K$. In particular, taking the fundamental group ... More

Measuring communication complexity using instance complexity with oraclesJan 19 2009We establish a connection between non-deterministic communication complexity and instance complexity, a measure of information based on algorithmic entropy. Let $\overline{x}$, $\overline{y}$ and $Y_1(\overline{x})$ be respectively the input known by ... More

Ab initio Hartree-Fock with electronic correlation study of the electronic properties of MgB2Mar 23 2001We performed all-electron ab initio self-consistent field Hartree-Fock linear combination of atomic orbital, in which electronic correlation using density functional were included to perform electronic calculations in MgB2 new superconductor. Superconductivity ... More

An Equivariance Theorem with Applications to Renaming (Preliminary Version)Feb 24 2011In the renaming problem, each process in a distributed system is issued a unique name from a large name space, and the processes must coordinate with one another to choose unique names from a much smaller name space. We show that lower bounds on the solvability ... More

Evolution of cooperation in a particular case of the infinitely repeated Prisoner's Dilemma with three strategiesSep 03 2015We will study a population of individuals playing the infinitely repeated Prisoner's Dilemma under replicator dynamics. The population consists of three kinds of individuals using the following reactive strategies: ALLD (individuals which always defect), ... More

Unbeatable Set Consensus via Topological and Combinatorial ReasoningMay 24 2016The set consensus problem has played an important role in the study of distributed systems for over two decades. Indeed, the search for lower bounds and impossibility results for this problem spawned the topological approach to distributed computing, ... More

Forcing theory for transverse trajectories of surface homeomorphismsMar 31 2015Nov 20 2015This paper studies homeomorphisms of surfaces isotopic to the identity by means of purely topological methods and Brouwer theory. The main development is a novel theory of orbit forcing using maximal isotopies and transverse foliations. This allows us ... More

Automated Feedback Generation for Introductory Programming AssignmentsApr 08 2012Nov 16 2012We present a new method for automatically providing feedback for introductory programming problems. In order to use this method, we need a reference implementation of the assignment, and an error model consisting of potential corrections to errors that ... More

Shadowing by non uniformly hyperbolic periodic points and uniform hyperbolicityJun 01 2006We prove that, under a mild condition on the hyperbolicity of its periodic points, a map $g$ which is topologically conjugated to a hyperbolic map (respectively, an expanding map) is also a hyperbolic map (respectively, an expanding map). In particular, ... More

Inferring SQL Queries Using Program SynthesisAug 09 2012Developing high-performance applications that interact with databases is a difficult task, as developers need to understand both the details of the language in which their applications are written in, and also the intricacies of the relational model. ... More

The mass function and distribution of velocity dispersions for UZC groups of galaxiesAug 08 2003We measure the distribution of velocity dispersions of groups of galaxies identified in the UZC catalog; we use the distribution to derive the group mass function. We introduce a new method which makes efficient use of the entire magnitude limited catalog. ... More

The Evolution of a Primordial Galactic Magnetic FieldSep 04 1996We consider the hypothesis that galactic magnetic fields are primordial. We also discuss the various objections to this hypothesis. We assume that there was a magnetic field present in the galactic plasma before the galaxy formed. After the galactic disk ... More

One-loop corrections for Higgs-portal dark matterAug 02 2016Models endowed with Higgs portals can probe into the hidden sectors of particle physics while providing stable dark matter candidates. Previous tree-level computations in such scenarios have shown that experimental bounds constrain dark matter to a very ... More

Vortices and domain walls in a Chern-Simons theory with magnetic moment interactionFeb 15 1997We study the structure and properties of vortices in a recently proposed Abelian Maxwell-Chern-Simons model in $2 +1 $ dimensions. The model which is described by gauge field interacting with a complex scalar field, includes two parity and time violating ... More

Excited-state phase transition leading to symmetry-breaking steady states in the Dicke modelSep 24 2012We study the phase diagram of the Dicke model in terms of the excitation energy and the radiation-matter coupling constant $\lambda$. Below a certain critical value $\lambda_c$ of the coupling constant $\lambda$ all the energy levels have a well-defined ... More

Random matrix models of stochastic integral type for free infinitely divisible distributionsMay 20 2010Jan 19 2012The Bercovici-Pata bijection maps the set of classical infinitely divisible distributions to the set of free infinitely divisible distributions. The purpose of this work is to study random matrix models for free infinitely divisible distributions under ... More

Downturn LGD: A More Conservative Approach for Economic Decline PeriodsAug 03 2014The purpose of this paper is to identify a relevant statistical correlation between rate of default, RD, and loss given default, LGD, in a major Brazilian financial institution Retail Home Equity exposure rated using the IRB approach, so that we may find ... More

Differentiability of thermodynamical quantities in non-uniformly expanding dynamicsMay 24 2012Feb 06 2016In this paper we study the ergodic theory of a robust non-uniformly expanding maps where no Markov assumption is required. We prove that the topological pressure is differentiable as a function of the dynamics and analytic with respect to the potential. ... More

Extremely rare interbreeding events can explain Neanderthal DNA in modern humansMar 23 2011Jun 03 2011Considering the recent experimental discovery of Green et al that present day non-Africans have 1 to 4% of their nuclear DNA of Neanderthal origin, we propose here a model which is able to quantify the interbreeding events between Africans and Neanderthals ... More

Nakayama automorphism of quasi-commutative skew PBW extensions over AS-regular algebrasNov 29 2017Graded quasi-commutative skew PBW extensions are isomorphic to graded iterated Ore extensions of endomorphism type, whence graded quasi-commutative skew PBW extensions with coefficients in AS-regular algebras are skew Calabi-Yau and the Nakayama automorphism ... More

A level-set multigrid technique for nonlinear diffusion in the numerical simulation of marble degradation under chemical pollutantsFeb 19 2019Having in mind the modelling of marble degradation under chemical pollutants, e.g. the sulfation process, we consider governing nonlinear diffusion equations and their numerical approximation. The space domain of a computation is the pristine marble object ... More