Results for "Leonardo Martínez-Sandoval"

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Depth with respect to a family of convex setsDec 11 2016We propose a notion of depth with respect to a finite family $\mathcal{F}$ of convex sets in $\mathbb{R}^d$ which we call $\text{dep}_\mathcal{F}$. We begin showing that $\text{dep}_\mathcal{F}$ satisfies some expected properties for a measure of depth ... More
A Tutte polynomial inequality for lattice path matroidsOct 02 2015Jun 20 2016Let $M$ be a matroid without loops or coloops and let $T(M;x,y)$ be its Tutte polynomial. In 1999 Merino and Welsh conjectured that $$\max(T(M;2,0), T(M;0,2))\geq T(M;1,1)$$ holds for graphic matroids. Ten years later, Conde and Merino proposed a multiplicative ... More
Further Consequences of the Colorful Helly HypothesisMar 16 2018Let $\mathcal{F}$ be a family of convex sets in ${\mathbb R}^d$, which are colored with $d+1$ colors. We say that $\mathcal{F}$ satisfies the Colorful Helly Property if every rainbow selection of $d+1$ sets, one set from each color class, has a non-empty ... More
A sunflower anti-Ramsey theorem and its applicationsMay 19 2015A $h$-sunflower in a hypergraph is a family of edges with $h$ vertices in common. We show that if we colour the edges of a complete hypergraph in such a way that any monochromatic $h$-sunflower has at most $\lambda$ petals, then it contains a large rainbow ... More
Triangle areas determined by arrangements of planar linesFeb 08 2019A widely investigated subject in combinatorial geometry, originated from Erd\H{o}s, is the following. Given a point set $P$ of cardinality $n$ in the plane, how can we describe the distribution of the determined distances? This has been generalized in ... More
Codimension two and three Kneser TransversalsJan 04 2016Sep 27 2016Let $k,d,\lambda \geqslant 1$ be integers with $d\geqslant \lambda $ and let $X\subset\mathbb{R}^{d}$ be a finite set. A $(d-\lambda)$-plane $L$ transversal to the convex hull of all $k$-sets of $X$ is called Kneser transversal. If in addition $L$ contains ... More
A Tutte polynomial inequality for lattice path matroidsOct 02 2015Oct 27 2016Let $M$ be a matroid without loops or coloops and let $T(M;x,y)$ be its Tutte polynomial. In 1999 Merino and Welsh conjectured that $$\max(T(M;2,0), T(M;0,2))\geq T(M;1,1)$$ holds for graphic matroids. Ten years later, Conde and Merino proposed a multiplicative ... More
Unified formalism for the generalized kth-order Hamilton-Jacobi problemOct 03 2013May 19 2014The geometric formulation of the Hamilton-Jacobi theory enables us to generalize it to systems of higher-order ordinary differential equations. In this work we introduce the unified Lagrangian-Hamiltonian formalism for the geometric Hamilton-Jacobi theory ... More
Geometric Hamilton-Jacobi theory for higher-order autonomous systemsSep 09 2013May 19 2014The geometric framework for the Hamilton-Jacobi theory is used to study this theory in the ambient of higher-order mechanical systems, both in the Lagrangian and Hamiltonian formalisms. Thus, we state the corresponding Hamilton-Jacobi equations in these ... More
Detection of vertical muons with the HAWC water Cherenkov detectors and its application to gamma/hadron discriminationAug 30 2017The HAWC observatory reconstructs atmospheric showers induced by very high-energy primary cosmic- or gamma-rays. Cosmic-rays with hadronic nature are several orders of magnitude more frequent than primary gammas and therefore it is necessary to perform ... More
ASB1 differential methylation in ischaemic cardiomyopathy. Relationship with left ventricular performance in end stage heart failure patientsApr 04 2017Aims: Ischaemic cardiomyopathy (ICM) leads to impaired contraction and ventricular dysfunction causing high rates of morbidity and mortality. Epigenomics allows the identification of epigenetic signatures in human diseases. We analyse the differential ... More
Complete Kneser TransversalsNov 04 2015Aug 12 2016Let $k,d,\lambda\geqslant1$ be integers with $d\geqslant\lambda $. Let $m(k,d,\lambda)$ be the maximum positive integer $n$ such that every set of $n$ points (not necessarily in general position) in $\mathbb{R}^{d}$ has the property that the convex hulls ... More
Dynamics in two networks based on stocks of the US stock marketAug 07 2014Sep 01 2014We follow the main stocks belonging to the New York Stock Exchange and to Nasdaq from 2003 to 2012, through years of normality and of crisis, and study the dynamics of networks built on two measures expressing relations between those stocks: correlation, ... More
Cluster formation and evolution in networks of financial market indicesNov 22 2011Using data from world stock exchange indices prior to and during periods of global financial crises, clusters and networks of indices are built for different thresholds and diverse periods of time, so that it is then possible to analyze how clusters are ... More
A Map of the Brazilian Stock MarketJul 21 2011Mar 28 2013We use the correlation matrix of stocks returns in order to create maps of the S\~ao Paulo Stock Exchange (BM&F-Bovespa), Brazil's main stock exchange. The data reffer to the year 2010, and the correlations between stock returns lead to the construction ... More
The hypergeneralized Heun equation in QFT in curved space-timesMay 28 2008In this article we show for the first time the role played by the hypergeneralized Heun equation (HHE) in the context of Quantum Field Theory in curved space-times. More precisely, we find suitable transformations relating the separated radial and angular ... More
Structure and causality relations in a global network of financial companiesOct 21 2013This work uses the stocks of the 197 largest companies in the world, in terms of market capitalization, in the financial area in the study of causal relationships between them using Transfer Entropy, which is calculated using the stocks of those companies ... More
Differential Calculus on Iso_q (N), Quantum Poincare' Algebra and q - GravityDec 22 1993Jan 06 1994We present a general method to deform the inhomogeneous algebras of the $B_n,C_n,D_n$ type, and find the corresponding bicovariant differential calculus. The method is based on a projection from $B_{n+1}, C_{n+1}, D_{n+1}$. For example we obtain the (bicovariant) ... More
Some Results on Infinite Dimensional Riemannian GeometryApr 18 2003Apr 29 2003In this paper we will investigate the global properties of complete Hilbert manifolds with upper and lower bounded sectional curvature. We shall prove the Focal Index Lemma that we will allow us to extend some classical results of finite dimensional Riemannian ... More
Análise Assintótica de Soluções de Equações Difusivas Não-Lineares via Métodos de Escalas MúltiplasMay 11 2006Mar 14 2011In the present work we shall describe and apply the techniques of the Renormalization Group - based in data rescaling and operator renormalizing - and of Homogenization - that substitutes, in a certain limit, a periodically inhomogeneous medium by a homogeneous ... More
Some Remarks on Robin-Laplacian EigenvaluesSep 14 2017We study some properties of Laplacian eigenvalues with negative Robin boundary conditions. We will show some monotonicity properties on annuli of the first eigenvalue by means of shape optimization techniques.
The Fundamental Equations of Point, Fluid and Wave Dynamics in the De Sitter-Fantappie-Arcidiacono Projective Relativity TheoryJan 23 2009A review is presented of the fundamental equations of point, perfect incompressible fluid and wave dynamics in the Fantappie-Arcidiacono theory of projective relativity, also known as De Sitter relativity. Compared to the original works, some deductions ... More
Fantappié-Arcidiacono theory of relativity versus recent cosmological evidences : a preliminary comparisonFeb 21 2007May 10 2007Notwithstanding the Fantappie-Arcidiacono theory of relativity was introduced more than half a century ago, its observational confirmations in cosmology (the only research field where its predictions differ from those of the Einsteinian relativity) are ... More
Bouligand-Severi $k$-tangents and strongly semisimple MV-algebrasJul 22 2013An algebra $A$ is said to be strongly semisimple if every principal congruence of $A$ is an intersection of maximal congruences. We give a geometrical characterisation of strongly semisimple MV-algebras in terms of Bouligand-Severi $k$-tangents. The latter ... More
Thermal momentum distribution from shifted boundary conditionsOct 19 2011At finite temperature the distribution of the total momentum is an observable characterizing the thermal state of a field theory, and its cumulants are related to thermodynamic potentials. In a relativistic system at zero chemical potential, for instance, ... More
Specialization of polynomial covers of prime degreeOct 09 2002Let K be a complete field of unequal characteristics $(0,p)$. The aim of this paper is to describe the the semi-stable models for covers $\bold P^1_K@>>>\bold P^1_K$ of degree p, unramified outside $r\leq p$ points and totally ramified above one of them, ... More
Extended Lie derivatives and a new formulation of D=11 supergravityApr 28 2006Apr 30 2006Introducing an extended Lie derivative along the dual of A, the three-form field of d=11 supergravity, the full diffeomorphism algebra of d=11 supergravity is presented. This algebra suggests a new formulation of the theory, where the three-form field ... More
Differential calculi on finite groupsMay 23 2000A brief review of bicovariant differential calculi on finite groups is given, with some new developments on diffeomorphisms and integration. We illustrate the general theory with the example of the nonabelian finite group S_3.
Study of the young stellar population of NGC 4214 using the Hubble Space TelescopeAug 26 2007We present an original study of the dwarf starburst galaxy NGC 4214. We use archival optical and UV images obtained with WFPC2 and STIS on-board the Hubble Space Telescope. We explain the process followed to obtain high-quality photometry and astrometry ... More
Archetypes, Causal Description and Creativity in Natural WorldJul 10 2006The idea, formulated for the first time by Pauli, of a "creativity" of natural processes on a quantum scale is briefly investigated, with particular reference to the phenomena, common throughout the biological world, involved in the amplification of microscopic ... More
A Pragmatic Smoothing Method for Improving the Quality of the Results in Atomic SpectroscopyMar 07 2016A new smoothing method for the improvement on the identification and quantification of spectral functions based on the previous knowledge of the signals that are expected to be quantified, is presented. These signals are used as weighted coefficients ... More
Thermal fluctuations propagation in the relativistic Euler regime: a causal appraisalMay 15 2009It is shown that thermal fluctuations present in a simple non-degenerate relativistic fluid satisfy a wave equation in the Euler regime. The characteristic propagation speeds are calculated and the classical expression for the speed of sound is recovered ... More
Harmonic Analysis and Superconformal Gauge Theories in Three Dimensions from AdS/CFT CorrespondenceFeb 14 2000Apr 15 2000In this thesis I review various aspects of the AdS_4/CFT_3 correspondence, where AdS_4 supergravity arises from compactification of M-theory on a coset space G/H and preserves N<8 supersymmetries. One focal point of my review is that the complete spectrum ... More
Tilted Ghost InflationJun 07 2004May 22 2005In a ghost inflationary scenario, we study the observational consequences of a tilt in the potential of the ghost condensate. We show how the presence of a tilt tends to make contact between the natural predictions of ghost inflation and the ones of slow ... More
Recent progress on chiral symmetry breaking in QCDNov 27 2015I review recent progress achieved on the lattice in the quantitative comprehension of chiral symmetry breaking in QCD. Emphasis is given to the recent precise computations of the spectral density of the Dirac operator in the continuum limit, and of the ... More
Finitary Process Evolution I: Information Geometry of Configuration Space and the Process-Replicator DynamicsJul 12 2018Jul 25 2018This report presents some fundamental mathematical results towards elucidating the information-geometric underpinnings of evolutionary modelling schemes for (quasi-)stationary discrete stochastic processes. The model class under consideration is that ... More
Obtaining a New Representation for the Golden Ratio by Solving a Biquadratic EquationAug 27 2002Nov 11 2014In the present work we show how different ways to solve biquadratic equations can lead us to different representations of its solutions. A particular equation which has the golden ratio and its reciprocal as solutions is shown as an example.
Super Star Clusters in the Blue Dwarf Galaxy UM 462Jul 03 2003I present optical observations of the Blue Compact Dwarf Galaxy UM 462. The images of this galaxy show several bright compact sources. A careful study of these sources has revealed their nature of young Super Star Clusters. The ages determined from the ... More
Noncommutative geometry and physics: a review of selected recent resultsMay 23 2000Aug 02 2000This review is based on two lectures given at the 2000 TMR school in Torino. We discuss two main themes: i) Moyal-type deformations of gauge theories, as emerging from M-theory and open string theories, and ii) the noncommutative geometry of finite groups, ... More
On G/H geometry and its use in M-theory compactificationsDec 30 1999The Riemannian geometry of coset spaces is reviewed, with emphasis on its applications to supergravity and M-theory compactifications. Formulae for the connection and curvature of rescaled coset manifolds are generalized to the case of nondiagonal Killing ... More
The Lagrangian of q-Poincare' GravityFeb 07 1994Feb 17 1994The gauging of the q-Poincar\'e algebra of ref. hep-th 9312179 yields a non-commutative generalization of the Einstein-Cartan lagrangian. We prove its invariance under local q-Lorentz rotations and, up to a total derivative, under q-diffeomorphisms. The ... More
On the quantum Poincare' groupDec 02 1992The inhomogeneous quantum groups $IGL_q(n)$ are obtained by means of a particular projection of $GL_q(n+1)$. The bicovariant differential calculus on $GL_q(n)$ is likewise projected into a consistent bicovariant calculus on $IGL_q(n)$. Applying the same ... More
Gauge theories of quantum groupsMay 28 1992We find two different q-generalizations of Yang-Mills theories. The corresponding lagrangians are invariant under the q-analogue of infinitesimal gauge transformations. We explicitly give the lagrangian and the transformation rules for the bicovariant ... More
Choosing the Right Relativity for QFTFeb 09 2009Jan 30 2012When speaking of the unification of quantum mechanics and relativity, one normally refers to special relativity (SR) or to Einstein general relativity (GR). The Dirac and Klein-Gordon wave equations are an example of unification of quantum concepts and ... More
Lame curves with bad reductionNov 14 2006Nov 15 2006Lame curves are a particular class of elliptic curves (with a torsion point attached to them) which naturally arise when studying Lame operators with finite monodromy. They can be realized as covers of the projective line unramified outside three points ... More
A lattice perspective of kaon phenomenologyNov 29 2003I review recent lattice computations of the matrix element relevant for K0-K0bar mixing and discuss the advantages of fermions with an exact chiral symmetry to compute K->pipi amplitudes.
Inverse scattering on conformally compact manifoldsMar 09 2008Mar 06 2009We study inverse scattering for $\Delta_g+V$ on $(X,g)$ a conformally compact manifold with metric $g,$ with variable sectional curvature $-\alf^2(y)$ at the boundary and $V\in C^\infty(X)$ not vanishing at the boundary. We prove that the scattering matrix ... More
A geometric Hall-type theoremDec 20 2014Jan 14 2015We introduce a geometric generalization of Hall's marriage theorem. For any family $F = \{X_1, \dots, X_m\}$ of finite sets in $\mathbb{R}^d$, we give conditions under which it is possible to choose a point $x_i\in X_i$ for every $1\leq i \leq m$ in such ... More
The SU(2)-character varieties of torus knotsFeb 15 2012Feb 23 2012Let G be the fundamental group of the complement of the torus knot of type (m,n). We study the relationship between SU(2) and SL(2,C)-representations of this group, looking at their characters. Using the description of the SL(2,C)-character variety of ... More
Higher-order Variational Calculus on Lie algebroidsJan 26 2015The equations for the critical points of the action functional defined by a Lagrangian depending on higher-order derivatives of admissible curves on a Lie algebroid are found. The relation with Euler-Poincar\'e and Lagrange Poincar\'e type equations is ... More
Linearization of nonlinear connections on vector and affine bundles, and some applicationsNov 18 2017A linear connection is associated to a nonlinear connection on a vector bundle by a linearization procedure. Our definition is intrinsic in terms of vector fields on the bundle. For a connection on an affine bundle our procedure can be applied after homogenization ... More
Points defining triangles with distinct circumradiiFeb 25 2014Paul Erdos asked if, among sufficiently many points in general position, there are always $k$ points such that all the circles through $3$ of these $k$ points have different radii. He later proved that this is indeed the case. However, he overlooked a ... More
Cosmological bulk viscosity, the Burnett regime, and the BGK equationOct 25 2002Einstein's field equations in FRW space-times are coupled to the BGK equation in order to derive the stress energy tensor including dissipative effects up to second order in the thermodynamical forces. The space-time is assumed to be matter-dominated, ... More
The thermal and kinematic Sunyaev-Zel'dovich effects revisitedOct 16 2003This paper shows that a simple convolution integral expression based on the mean value of the isotropic frequency distribution corresponding to photon scattering off electrons leads to useful analytical expressions describing the thermal Sunyaev-Zel'dovich ... More
Note on the Sunyaev-Zel'dovich thermal effectMay 08 2003Jun 12 2003In a previous publication we have derived an expression for the full distorted spectrum arising when the photons of the cosmic background radiation are absorbed and emitted by an optically thin gas. The expression simply adds up the effects of the joint ... More
Shocks in financial markets, price expectation, and damped harmonic oscillatorsMar 10 2011Sep 24 2011Using a modified damped harmonic oscillator model equivalent to a model of market dynamics with price expectations, we analyze the reaction of financial markets to shocks. In order to do this, we gather data from indices of a variety of financial markets ... More
Evolution of statistical averages: an interdisciplinary proposal using the Chapman-Enskog methodJul 18 2014Feb 27 2015This work examines the idea of applying the Chapman-Enskog (CE) method for approximating the solution of the Boltzmann equation beyond the realm of physics, using an information theory approach. Equations describing the evolution of averages and their ... More
Light scattering test regarding the relativistic nature of heatNov 11 2005The dynamic structure factor of a simple relativistic fluid is calculated. The coupling of acceleration with the heat flux present in Eckart's version of irreversible relativistic thermodynamics is examined using the Rayleigh-Brillouin spectrum of the ... More
The Sunyaev-Zel'dovich effect revisitedJul 10 2002Jul 12 2002The well known Sunyaev-Zel'dovich (SZ) effect is reexamined using a Doppler shift type mechanism arising from the scattering of photons by electrons in an optically thin gas. The results are in excellent agreement with the observational data as well as ... More
Hypercubes circumscribed in hyperspheres: a constant growth ratio for volumes at large dimensionsNov 04 2004This note shows that an interesting property arises when considering the relation between the hypersphere volumes at dimensions $n+1$ and $n$, if the hyperspheres circumscribe unitary hypercubes in $n+1$ and $n$ dimensions, respectively . In the limit ... More
The statistical nature of the second order corrections to the thermal SZESep 06 2004Sep 20 2004This paper shows that the accepted expressions for the second order corrections in the parameter $z$ to the thermal Sunyaev-Zel'dovich effect can be accurately reproduced by a simple convolution integral approach. This representation allows to separate ... More
Electron correlations in a C$_{20}$ fullerene cluster: A lattice density-functional study of the Hubbard modelApr 29 2005The ground-state properties of C$_{20}$ fullerene clusters are determined in the framework of the Hubbard model by using lattice density-functional theory (LDFT) and scaling approximations to the interaction-energy functional. Results are given for the ... More
Density-Matrix functional theory of strongly-correlated lattice fermionsJul 17 2002A density functional theory (DFT) of lattice fermion models is presented, which uses the single-particle density matrix gamma_{ij} as basic variable. A simple, explicit approximation to the interaction-energy functional W[gamma] of the Hubbard model is ... More
Jeans instability analysis in the presence of heat in Eckart's frameJan 11 2011It is shown that the coupling of heat with acceleration first proposed by Eckart would have an overwhelming effect in the growth of density mass fluctuations, even in non-relativistic fluids in the presence of a gravitational field. Gravitational effects ... More
Theory of the Hilbert SpectrumApr 28 2015Sep 25 2015This paper is a contribution to the old problem of representing a signal in the coordinates of time and frequency. As the starting point, we abandon Gabor's complex extension and re-evaluate fundamental principles of time-frequency analysis. We provide ... More
The Higgs boson: from the lattice to LHCNov 27 2009Nov 09 2011We discuss the triviality and spontaneous symmetry breaking scenario where the Higgs boson without self-interaction coexists with spontaneous symmetry breaking. We argue that non perturbative lattice investigations support this scenario. Moreover, from ... More
Lattice Background Effective Action: a ProposalJul 04 1996We propose a method based on the Schr\"odinger functional for computing on the lattice the gauge invariant effective action for external background fields. We check this method by studying the U(1) lattice gauge theory in presence of a constant magnetic ... More
Dual superconductivity in the SU(2) pure gauge vacuum: a lattice studyApr 13 1995We investigate the dual superconductivity hypothesis in pure SU(2) lattice gauge theory. We focus on the dual Meissner effect by analyzing the distribution of the color fields due to a static quark-antiquark pair. We find evidence of the dual Meissner ... More
Probing the non-perturbative dynamics of SU(2) vacuumMar 02 1999The vacuum dynamics of SU(2) lattice gauge theory is studied by means of a gauge-invariant effective action defined using the lattice Schr\"odinger functional. Numerical simulations are performed both at zero and finite temperature. The vacuum is probed ... More
Minimal AdS_3Jul 05 2005Jan 26 2006We show that Type IIB string theory on AdS_3 X S^3 X M_4 with p units of NS flux contains an integrable subsector, isomorphic to the minimal (p,1) bosonic string. To this end, we construct a topological string theory with target space Euclidean AdS_3 ... More
Quantum Protocols within Spekkens' Toy ModelAug 31 2016Quantum mechanics is known to provide significant improvements in information processing tasks when compared to classical computational models. These advantages range from computational speeds-ups to security improvements. Here we study protocols based ... More
Generalized Hammersley Process and Phase Transition for Activated Random Walk ModelsDec 14 2008* ACTIVATED RANDOM WALK MODEL * This is a conservative particle system on the lattice, with a Markovian continuous-time evolution. Active particles perform random walks without interaction, and they may as well change their state to passive, then stopping ... More
Activated Random WalksJul 15 2015Lecture Notes. Minicourse given at the workshop "Activated Random Walks, DLA, and related topics" at IM\'eRA-Marseille, March 2015.
Introducing holographic flavor in an intensely magnetized quark-gluon plasmaJan 17 2019We present a construction that makes possible the application of gauge/gravity methods to study fundamental degrees of freedom in a quark-gluon plasma subject to a magnetic field as intense as that expected in high energy collisions. This is achieved ... More
An Eigenvalue problem for the Infinity-LaplacianNov 13 2012Feb 01 2013We study an eigenvalue problem for the infinity-Laplacian on bounded domains. We prove the existence of the principal eigenvalue and a corresponding positive eigenfunction. The work also contains existence results when the parameter, in the equation, ... More
Fast Hessenberg reduction of some rank structured matricesDec 13 2016We develop two fast algorithms for Hessenberg reduction of a structured matrix $A = D + UV^H$ where $D$ is a real or unitary $n \times n$ diagonal matrix and $U, V \in\mathbb{C}^{n \times k}$. The proposed algorithm for the real case exploits a two--stage ... More
Asymptotics of viscosity solutions to some doubly nonlinear parabolic equationsJul 31 2015Mar 23 2017We study asymptotic decay rates of viscosity solutions to some doubly nonlinear parabolic equations, including Trudinger's equation. We also prove a Phragm\'en-Lindel\"of type result and show its optimality.
Orthogonal polynomial projection error measured in Sobolev norms in the unit diskMar 15 2015Nov 27 2015We study approximation properties of weighted $L^2$-orthogonal projectors onto the space of polynomials of degree less than or equal to $N$ on the unit disk where the weight is of the generalized Gegenbauer form $x \mapsto (1-|x|^2)^\alpha$. The approximation ... More
Quasi-Carousel TournamentsMar 13 2015Apr 15 2015A tournament is called locally transitive if the outneighbourhood and the inneighbourhood of every vertex are transitive. Equivalently, a tournament is locally transitive if it avoids the tournaments $W_4$ and $L_4$, which are the only tournaments up ... More
A Calabi's Type CorrespondenceJan 31 2019Calabi observed that there is a natural correspondence between the solutions of the minimal surface equation in $\mathbb{R}^3$ with those of the maximal spacelike surface equation in $\mathbb{L}^3$. We are going to show how this correspondence can be ... More
Homogeneous bundles and the first eigenvalue of symmetric spacesSep 13 2007Mar 16 2008We prove the stability of the Gieseker point of an irreducible homogeneous bundle over a rational homogeneous space. As an application we get a sharp upper estimate for the first eigenvalue of the Laplacian of an arbitrary Kaehler metric on a compact ... More
Dust and Super Star Clusters in NGC 5253Dec 15 2003We present new observations of the famous starburst galaxy NGC 5253 which owes its celebrity to possibly being the youngest and closest starburst galaxy known. Our observations in the infrared and millimeter contribute to shed light on the properties ... More
Examples of irreducible automorphisms of handlebodiesMar 02 2004Automorphisms of handlebodies arise naturally in the a classification of automorphisms of three-manifolds. Among automorphisms of handlebodies, there are certain automorphisms called irreducible (or generic), which are analogues of pseudo-Anosov automorphisms ... More
A Game-Theoretic Approach to Robust Fusion and Kalman Filtering Under Unknown CorrelationsOct 04 2016This work addresses the problem of fusing two random vectors with unknown cross-correlations. We present a formulation and a numerical method for computing the optimal estimate in the minimax sense. We extend our formulation to linear measurement models ... More
Energy-momentum tensor on the lattice: non-perturbative renormalization in Yang--Mills theoryMar 24 2015Jun 04 2015We construct an energy-momentum tensor on the lattice which satisfies the appropriate Ward Identities (WIs) and has the right trace anomaly in the continuum limit. It is defined by imposing suitable WIs associated to the Poincare` invariance of the continuum ... More
Chiral symmetry breaking and the Banks--Casher relation in lattice QCD with Wilson quarksDec 18 2008The Banks--Casher relation links the spontaneous breaking of chiral symmetry in QCD to the presence of a non-zero density of quark modes at the low end of the spectrum of the Dirac operator. Spectral observables like the number of modes in a given energy ... More
Isometry-invariant geodesics and the fundamental group, IIApr 22 2015We show that on a closed Riemannian manifold with fundamental group isomorphic to $\mathbb{Z}$, other than the circle, every isometry that is homotopic to the identity possesses infinitely many invariant geodesics. This completes a recent result of the ... More
Analytical results on the Muller's ratchet effect in growing populationsFeb 24 2009Fontanari et al introduced [Phys. Rev. Lett. 91, 218101 (2003)] a model for studying the Muller's ratchet phenomenon in growing asexual populations. They studied two situations, either including or not a death probability for each newborn, but were able ... More
Segre invariant and a stratification of the moduli space of coherent systemsOct 13 2018The aim of this paper is to generalize the $m-$Segre invariant for vector bundles to coherent systems. Let $X$ be a non-singular irreducible complex projective curve of genus $g$ over $\mathbb{C}$ and $(E,V)$ be a coherent system on $X$ of type $(n,d,k)$. ... More
Scalar Resonances in Axially Symmetric SpacetimesMar 12 2015We study properties of resonant solutions to the scalar wave equation in several axially symmetric spacetimes. We prove that non-axial resonant modes do not exist neither in the Lanczos dust cylinder, the $(2+1)$ extreme BTZ spacetime nor in a class of ... More
An internal mechanism for the anti-glitch observed in AXP 1E 2259+586Mar 12 2015Magnetars are fascinating objects that are thought to be neutron stars powered by their strong internal magnetic fields. Clear evidence of a sudden spin-down was detected in the Anomalous X-ray Pulsar AXP 1E 2259+586, an object cataloged as a magnetar. ... More
Noncommutative supergravity in D=3 and D=4Feb 23 2009Mar 12 2009We present a noncommutative D=3, N=1 supergravity, invariant under diffeomorphisms, local U(1,1) noncommutative \star-gauge transformations and local \star-supersymmetry. Its commutative limit is the usual D=3 pure supergravity, without extra fields. ... More
Noncommutative D=4 gravity coupled to fermionsFeb 23 2009We present a noncommutative extension of Einstein-Hilbert gravity in the context of twist-deformed space-time, with a $\star$-product associated to a quite general triangular Drinfeld twist. In particular the $\star$-product can be chosen to be the usual ... More
R-Matrix Formulation of the Quantum Inhomogeneous Groups Iso_qr(N) and Isp_qr(N)Nov 05 1994The quantum commutations $RTT=TTR$ and the orthogonal (symplectic) conditions for the inhomogeneous multiparametric $q$-groups of the $B_n,C_n,D_n$ type are found in terms of the $R$-matrix of $B_{n+1},C_{n+1},D_{n+1}$. A consistent Hopf structure on ... More
Noncommutative Gravity SolutionsJun 15 2009Dec 02 2009We consider noncommutative geometries obtained from a triangular Drinfeld twist and review the formulation of noncommutative gravity. A detailed study of the abelian twist geometry is presented, including the fundamental theorem of noncommutative Riemannian ... More
Probing Confinement with Chromomagnetic FieldsSep 13 2002Using the lattice Schr\"odinger functional we study vacuum dynamics of SU(3) gauge theory at finite temperature. The vacuum is probed by means of an external constant Abelian chromomagnetic field. We find that by increasing the strength of the applied ... More
Exploring the Unstable Modes Dynamics by the Lattice Schrodinger FunctionalJul 10 1996We analyze the problem of the Nielsen-Olesen unstable modes in the $SU(2)$ lattice gauge theory by means of a recently introduced gauge-invariant effective action. We perform numerical simulations in the case of a constant Abelian chromomagnetic field. ... More
Probing the QCD Vacuum Using External FieldsFeb 13 2006The QCD vacuum can be studied using external fields. We report here results respectively obtained probing the lattice QCD vacuum by means of an abelian monopole field and of an abelian chromomagnetic field
SU(2) vacuum dynamics in applied external magnetic fieldSep 09 1998The vacuum dynamics of SU(2) lattice gauge theory is studied by means of a gauge-invariant effective action, both at zero and finite temperature. Working with lattices up to 32^4 we check the scaling of the energy density with the magnetic length. We ... More
Line Maps in Cluttered EnvironmentsFeb 20 2014This paper uses the smoothing and mapping framework to solve the SLAM problem in indoor environments; focusing on how some key issues such as feature extraction and data association can be handled by applying probabilistic techniques. For feature extraction, ... More