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Results for "Artur Costa-Pazo"

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Deep Anomaly Detection for Generalized Face Anti-SpoofingApr 17 2019Face recognition has achieved unprecedented results, surpassing human capabilities in certain scenarios. However, these automatic solutions are not ready for production because they can be easily fooled by simple identity impersonation attacks. And although ... More
Generalized Presentation Attack Detection: a face anti-spoofing evaluation proposalApr 12 2019Over the past few years, Presentation Attack Detection (PAD) has become a fundamental part of facial recognition systems. Although much effort has been devoted to anti-spoofing research, generalization in real scenarios remains a challenge. In this paper ... More
Generating Sets of the Kernel Graph and the Inverse Problem in Synchronization TheoryJan 17 2016Mar 11 2016This paper analyses the construction of the kernel graph of a non-synchronizing transformation semigroup and introduces the inverse synchronization problem. Given a transformation semigroup $S\leq T_n$, we construct the kernel graph $\text{Gr}(S)$ by ... More
From quantum-codemaking to quantum code-breakingMar 19 1997This is a semi-popular overview of quantum entanglement as an important physical resource in the field of data security and quantum computing. After a brief outline of entanglement's key role in philosophical debates about the meaning of quantum mechanics ... More
The $n$th+1 Prime Number Limit FormulasAug 04 2016Aug 08 2016A new derivation of Golomb's limit formula for generating the $n$th$+1$ prime number is presented. The limit formula is derived by extracting $p_{n+1}$ from Euler's prime product representation of the Riemann zeta function $\zeta(s)$ in the limit as $s$ ... More
Locally small spaces with an applicationMar 03 2019We develop the theory of locally small spaces in a new simple language and apply this simplification to re-build the theory of locally definable spaces over structures with topologies.
Complex and Unpredictable CardanoJun 03 2008This purely recreational paper is about one of the most colorful characters of the Italian Renaissance, Girolamo Cardano, and the discovery of two basic ingredients of quantum theory, probability and complex numbers. The paper is dedicated to Giuseppe ... More
Density of positive Lyapunov exponents for SL(2,R) cocyclesApr 25 2010We show that SL(2,R) cocycles with a positive Lyapunov exponent are dense in all regularity classes and for all non-periodic dynamical systems. For Schr\"odinger cocycles, we show prevalence of potentials for which the Lyapunov exponent is positive for ... More
The Dirichlet problem for nonlocal Lévy-type operatorsFeb 03 2017May 31 2017We present the theory of the Dirichlet problem for nonlocal operators which are the generators of general pure-jump symmetric L\'evy processes whose L\'evy measures need not be absolutely continuous. We establish basic facts about the Sobolev spaces for ... More
Infinitely many local higher symmetries without recursion operator or master symmetry: integrability of the Foursov--Burgers system revisitedApr 12 2008Jan 19 2009We consider the Burgers-type system studied by Foursov, w_t &=& w_{xx} + 8 w w_x + (2-4\alpha)z z_x, z_t &=& (1-2\alpha)z_{xx} - 4\alpha z w_x + (4-8\alpha)w z_x - (4+8\alpha)w^2 z + (-2+4\alpha)z^3, (*) for which no recursion operator or master symmetry ... More
Representation stability on the cohomology of complements of subspace arrangementsNov 24 2017We study representation stability in the sense of Church and Farb of sequences of cohomology groups of complements of arrangements of linear subspaces in real and complex space as $S_n$-modules. We consider arrangement of linear subspaces defined by sets ... More
Time delay in the Kuramoto model with bimodal frequency distributionJun 15 2006We investigate the effects of a time-delayed all-to-all coupling scheme in a large population of oscillators with natural frequencies following a bimodal distribution. The regions of parameter space corresponding to synchronized and incoherent solutions ... More
Weak mixing properties of interval exchange transformations and translation flowsMay 10 2016Let $d >1$. In this paper we show that for an irreducible permutation $\pi$ which is not a rotation, the set of $[\lambda]\in \mathbb{P}_+^{d-1}$ such that the interval exchange transformation $f([\lambda],\pi)$ is not weakly mixing does not have full ... More
Consistent analysis of neutral- and charged-current neutrino scattering off carbonMay 22 2012Sep 11 2012Background: Good understanding of the cross sections for (anti)neutrino scattering off nuclear targets in the few-GeV energy region is a prerequisite for correct interpretation of results of ongoing and planned oscillation experiments. Purpose: Clarify ... More
High-energy limit of neutrino quasielastic cross sectionMar 18 2005Mar 23 2005It's a common knowledge that the quasielastic neutrino-neutron and antineutrino-proton cross sections tend to the same constant as (anti)neutrino energy becomes high. In this paper we calculate the exact expression of the limit in terms of the parameters ... More
Dynamic Quantum Tomography Model for Phase-Damping ChannelsSep 30 2015Dec 30 2015In this article we propose a dynamic quantum tomography model for open quantum systems with evolution given by phase-damping channels. Mathematically, these channels correspond to completely positive trace-preserving maps defined by the Hadamard product ... More
Convergence and Summability of Multiple Fourier series and generalized variationApr 24 2014In this paper we present results on convergence and Ces\`{a}ro summability of Multiple Fourier series of functions of bounded generalized variation.
Bornological quasi-metrizability in generalized topologyMay 17 2015Oct 17 2018A concept of quasi-metrizability with respect to a bornology of a generalized topological space in the sense of Delfs and Knebusch is introduced. Quasi-metrization theorems for generalized bornological universes are deduced. A uniform quasi-metrizability ... More
Dense definiteness and boundedness of composition operators in $L^2$-spaces via inductive limitsSep 13 2014The questions of dense definiteness and boundedness of composition operators in $L^2$-spaces are studied by means of inductive limits of operators. Methods based on projective systems of measure spaces and inductive limits of $L^2$-spaces are developed. ... More
Some monoids of Pisot matricesJun 11 2015We show that several monoids of non-negative integer matrices enjoy a Pisot property: each matrix in that monoid has only one eigenvalue with absolute value larger than one. These monoids come from multidimensional continued fractions, namely the fully ... More
Improving Viterbi is Hard: Better Runtimes Imply Faster Clique AlgorithmsJul 14 2016Nov 03 2016The classic algorithm of Viterbi computes the most likely path in a Hidden Markov Model (HMM) that results in a given sequence of observations. It runs in time $O(Tn^2)$ given a sequence of $T$ observations from a HMM with $n$ states. Despite significant ... More
Mimetic spectral element method for Hamiltonian systemsMay 13 2015There is a growing interest in the conservation of invariants when numerically solving a system of ordinary differential equations. Methods that exactly preserve these quantities in time are known as geometric integrators. In this paper we apply the recently ... More
Weak mixing properties of interval exchange transformations and translation flowsMay 10 2016Feb 05 2017Let $d >1$. In this paper we show that for an irreducible permutation $\pi$ which is not a rotation, the set of $[\lambda]\in \mathbb{P}_+^{d-1}$ such that the interval exchange transformation $f([\lambda],\pi)$ is not weakly mixing does not have full ... More
Improving Viterbi is Hard: Better Runtimes Imply Faster Clique AlgorithmsJul 14 2016The classic algorithm of Viterbi computes the most likely path in a Hidden Markov Model (HMM) that results in a given sequence of observations. It runs in time $O(Tn^2)$ given a sequence of $T$ observations from a HMM with $n$ states. Despite significant ... More
Optical vortex coronagraphy from soft spin-orbit masksSep 19 2016We report on a soft route towards optical vortex coronagraphy based on self-engineered electrically tunable vortex masks based on liquid crystal topological defects. These results suggest that a Nature-assisted technological approach to the fabrication ... More
Direct detection of quantum entanglementNov 11 2001Quantum entanglement, after playing a significant role in the development of the foundations of quantum mechanics, has been recently rediscovered as a new physical resource with potential commercial applications such as, for example, quantum cryptography, ... More
Weak mixing properties of interval exchange transformations and translation flowsMay 10 2016Nov 02 2016Let $d >1$. In this paper we show that for an irreducible permutation $\pi$ which is not a rotation, the set of $[\lambda]\in \mathbb{P}_+^{d-1}$ such that the interval exchange transformation $f([\lambda],\pi)$ is not weakly mixing does not have full ... More
The Hidden Subgroup Problem and Eigenvalue Estimation on a Quantum ComputerMar 20 1999A quantum computer can efficiently find the order of an element in a group, factors of composite integers, discrete logarithms, stabilisers in Abelian groups, and `hidden' or `unknown' subgroups of Abelian groups. It is already known how to phrase the ... More
The local power of the gradient testApr 30 2010Jul 12 2010The asymptotic expansion of the distribution of the gradient test statistic is derived for a composite hypothesis under a sequence of Pitman alternative hypotheses converging to the null hypothesis at rate $n^{-1/2}$, $n$ being the sample size. Comparisons ... More
Euroattractor: a brief introduction to Iterated Function SystemsOct 30 2002In this work we propose a definition of an Euroattractor: an attracting invariant measure of a certain iterated functions system (IFS). An IFS is defined by specifying a set of functions, defined in subsets of R^N or in a classical phase space, which ... More
Compactness and compactifications in generalized topologyFeb 06 2014A generalized topology in a set $X$ is a collection $\text{Cov}_X$ of families of subsets of $X$ such that the triple $(X,\bigcup \text{Cov}_X,\text{Cov}_X)$ is a generalized topological space in the sense of Delfs and Knebusch. In this work, notions ... More
Asymptotic and exact expansions of heat tracesDec 15 2014We study heat traces associated with positive unbounded operators with compact inverses. With the help of the inverse Mellin transform we derive necessary conditions for the existence of a short time asymptotic expansion. The conditions are formulated ... More
Quantum Algorithms: Entanglement Enhanced Information ProcessingMar 26 1998We discuss the fundamental role of entanglement as the essential nonclassical feature providing the computational speed-up in the known quantum algorithms. We review the construction of the Fourier transform on an Abelian group and the principles underlying ... More
Generic expanding maps without absolutely continuous invariant $σ$-finite measureAug 02 2006We show that a $C^1$-generic expanding map of the circle has no absolutely continuous invariant $\sigma$-finite measure.
Simplicity of Lyapunov spectra: proof of the Zorich-Kontsevich conjectureAug 25 2005We prove the Zorich-Kontsevich conjecture that the non-trivial Lyapunov exponents of the Teichm\"uller flow on (any connected component of a stratum of) the moduli space of Abelian differentials on compact Riemann surfaces are all distinct. By previous ... More
Reducibility or non-uniform hyperbolicity for quasiperiodic Schrodinger cocyclesJun 26 2003Apr 26 2007We show that for almost every frequency alpha \in \R \setminus \Q, for every C^omega potential v:\R/\Z \to R, and for almost every energy E the corresponding quasiperiodic Schrodinger cocycle is either reducible or nonuniformly hyperbolic. This result ... More
Towers for commuting endomorphisms, and combinatorial applicationsJul 24 2015Jan 28 2016We give an elementary proof of a generalization of Rokhlin's lemma for commuting non-invertible measure-preserving transformations, and we present several combinatorial applications.
Monotonic cocyclesOct 02 2013We develop a "local theory" of multidimensional quasiperiodic $\SL(2,\R)$ cocycles which are not homotopic to a constant. It describes a $C^1$-open neighborhood of cocycles of rotations and applies irrespective of arithmetic conditions on the frequency, ... More
New Examples of Kochen-Specker Type Configurations on Three QubitsJun 29 2012Oct 30 2012A new example of a saturated Kochen-Specker (KS) type configuration of 64 rays in 8-dimensional space (the Hilbert space of a triple of qubits) is constructed. It is proven that this configuration has a tropical dimension 6 and that it contains a critical ... More
Memory equations as reduced Markov processesApr 06 2018A large class of linear memory differential equations in one dimension, where the evolution depends on the whole history, can be equivalently described as a projection of a Markov process living in a higher dimensional space. Starting with such a memory ... More
Inner functions in weak Besov spacesJul 18 2013It is shown that inner functions in weak Besov spaces are precisely the exponential Blaschke products.
An almost-solvable model of complex network dynamicsFeb 26 2019We discuss a specific model, which we refer to as RandLOE, of a large multi-agent network whose dynamic is prescribed via a combination of deterministic local laws and random exogenous factors. The RandLOE approach lies outside the framework of Stochastic ... More
Smoothness of sets in Euclidean spacesSep 22 2010Dec 10 2010We study some properties of smooth sets in the sense defined by Hungerford. We prove a sharp form of Hungerford's Theorem on the Hausdorff dimension of their boundaries on Euclidean spaces and show the invariance of the definition under a class of automorphisms ... More
Spectral action for scalar perturbations of Dirac operatorsDec 17 2010We investigate the leading terms of the spectral action for odd-dimensional Riemannian spin manifolds with the Dirac operator perturbed by a scalar function. We calculate first two Gilkey-de Witt coefficients and make explicit calculations for the case ... More
Quasisymmetric robustness of the Collet-Eckmann condition in the quadratic familyMay 27 2001We consider quasisymmetric reparametrizations of the parameter space of the quadratic family. We prove that the set of quadratic maps which are either regular or Collet-Eckmann with polynomial recurrence of the critical orbit has full Lebesgue measure. ... More
Decoherence properties of arbitrarily long historiesDec 03 2004Within the decoherent histories formulation of quantum mechanics, we consider arbitrarily long histories constructed from a fixed projective partition of a finite-dimensional Hilbert space. We review some of the decoherence properties of such histories ... More
The physics of kHz QPOs---strong gravity's coupled anharmonic oscillatorsMay 03 2001We explain the origin of the puzzling high frequency peaks (QPOs) in the variability power spectra of accreting neutron stars and black holes as a non-linear 1:2 or 1:3 resonance between orbital and radial epicyclic motion. These resonances are present ... More
Semiclassical limits, Lagrangian states and coboundary equationsDec 25 2015Jan 25 2016Assume that $f$ is a continuous transformation $f:S^1 \to S^1$. We consider here the cases where $f$ is either the transformation $f(z)=z^2$ or $f$ is a smooth diffeomorphism of the circle $S^1$. Consider a fixed continuous potential $\tau:S^1=[0,1) \to ... More
Initial states and decoherence of historiesMay 14 2004We study decoherence properties of arbitrarily long histories constructed from a fixed projective partition of a finite dimensional Hilbert space. We show that decoherence of such histories for all initial states that are naturally induced by the projective ... More
Extremal solutions of Nevalinna-Pick problems and certain classes of inner functionsMay 14 2014May 15 2014Consider a scaled Nevanlinna-Pick interpolation problem and let $\Pi$ be the Blaschke product whose zeros are the nodes of the problem. It is proved that if $\Pi$ belongs to a certain class of inner functions, then the extremal solutions of the problem ... More
Statistical properties of unimodal maps: physical measures, periodic orbits and pathological laminationsJun 10 2003In this work, we relate the geometry of chaotic attractors of typical analytic unimodal maps to the behavior of the critical orbit. Our main result is an explicit formula relating the combinatorics of the critical orbit with the exponents of periodic ... More
Gibbs States and Gibbsian Specifications on the space $\mathbb{R}^{\mathbb{N}}$Apr 06 2019We are interested in the study of Gibbs and equilbrium probabilities on the lattice $\mathbb{R}^{\mathbb{N}}$. Consider the unilateral full-shift defined on the non-compact set $\mathbb{R}^{\mathbb{N}}$ and an $\alpha$-H\"older continuous potential $A$ ... More
Evidence for a BKT transition and a pseudogap phase in three-dimensional Gross-Neveu model at nonzero temperatureOct 16 2001We present results from Monte Carlo simulations of the three-dimensional Gross-Neveu model with a U(1) chiral symmetry at nonzero temperature. We provide evidence that the model undergoes a Berezinskii-Kosterlitz-Thouless transition in accordance with ... More
Solution for the problem of the game heads or tailsDec 02 2010Dec 07 2010In this paper, we describe the solution for a problem dealing with definite properties of binary sequences. This problem, proposed by Xavier Grandsart in the form of a mathematical contest, has been solved also by Maher Younan, Ph.D. student of Theoretical ... More
Viscosity of high crystal content melts: dependence on solid fractionOct 21 2005The rheological properties of suspensions containing high solid fractions are investigated. Attention is focused on viscosity of silicate and magmatic melt systems. A general empirical equation which describes the relative viscosity of suspensions as ... More
Comments on "Viscosity of high crystal content melts: dependence on solid fraction"Dec 19 2005Dec 21 2005Here we propose a simple modification of the parameterisation presented in Costa (2005) [Viscosity of high crystal content melts: dependence on solid fraction, Geophys. Res. Lett., 32, 2005] which improves all the main positive features of it, yet at ... More
Inner Functions with Derivatives in the Weak Hardy SpaceJun 14 2012It is proved that exponential Blaschke products are the inner functions whose derivative is in the weak Hardy space. Exponential Blaschke products are described in terms of their logarithmic means and also in terms of the behavior of the derivatives of ... More
Classical irregular block, N=2 pure gauge theory and Mathieu equationJul 01 2014Combining the semiclassical/Nekrasov-Shatashvili limit of the AGT conjecture and the Bethe/gauge correspondence results in a triple correspondence which identifies classical conformal blocks with twisted superpotentials and then with Yang-Yang functions. ... More
Statistical properties of unimodal maps: smooth families with negative Schwarzian derivativeMay 27 2001Jun 10 2003We prove that there is a residual set of families of smooth or analytic unimodal maps with quadratic critical point and negative Schwarzian derivative such that almost every non-regular parameter is Collet-Eckmann with subexponential recurrence of the ... More
Invertibility Threshold for Nevanlinna Quotient AlgebrasApr 15 2019Let $\mathcal{N}$ be the Nevanlinna class and let $B$ be a Blaschke product. It is shown that the natural invertibility criterion in the quotient algebra $\mathcal{N} / B \mathcal{N}$, that is, $|f| \ge e^{-H} $ on the set $B^{-1}\{0\}$ for some positive ... More
A Survey of e-Biodiversity: Concepts, Practices, and ChallengesSep 29 2018The unprecedented size of the human population, along with its associated economic activities, have an ever increasing impact on global environments. Across the world, countries are concerned about the growing resource consumption and the capacity of ... More
The problem of a self-gravitating scalar field with positive cosmological constantJun 19 2012Jan 15 2013We study the Einstein-scalar field system with positive cosmological constant and spherically symmetric characteristic initial data given on a truncated null cone. We prove well-posedness, global existence and exponential decay in (Bondi) time, for small ... More
New distinct curves having the same complement in the projective planeNov 29 2010In 1984, H. Yoshihara conjectured that if two plane irreducible curves have isomorphic complements, they are projectively equivalent, and proved the conjecture for a special family of unicuspidal curves. Recently, J. Blanc gave counterexamples of degree ... More
Recent QCD results from the TevatronOct 10 2015Four years after the shutdown of the Tevatron proton-antiproton collider, the two Tevatron experiments, CDF and DZero, continue producing important results that test the theory of the strong interaction, Quantum Chromodynamics (QCD). The experiments exploit ... More
Form Factors of 2-D Integrable Models Using Radial QuantizationJun 22 1994We review some ideas from a recent construction which introduced the notion of vertex operators and form factors as vacuum expectation values of related vertex operators in the space of fields. The vertex operators are constructed explicitly in radial ... More
Isentropic thermodynamics and scalar-mesons properties near the QCD critical end pointOct 19 2016We investigate the QCD phase diagram and the location of the critical end point (CEP) in the SU(2) Polyakov$-$Nambu$-$Jona-Lasinio model with entanglement interaction giving special attention to the $\pi$ and $\sigma$-mesons properties, namely the decay ... More
A FFT-based finite-difference solver for massively-parallel direct numerical simulations of turbulent flowsFeb 28 2018Aug 02 2018We present an efficient solver for massively-parallel direct numerical simulations of incompressible turbulent flows. The method uses a second-order, finite-volume pressure-correction scheme, where the pressure Poisson equation is solved with the method ... More
Spherical linear waves in de Sitter spacetimeJul 05 2011May 25 2012We apply Christodoulou's framework, developed to study the Einstein-scalar field equations in spherical symmetry, to the linear wave equation in de Sitter spacetime, as a first step towards the Einstein-scalar field equations with positive cosmological ... More
Non-minimal coupling contribution to DIS at low $x$ in Holographic QCDApr 20 2018We consider the effect of including a non-minimal coupling between a $U(1)$ vector gauge field and the graviton Regge trajectory in holographic QCD models. This coupling describes the QCD interaction between the quark bilinear electromagnetic current ... More
New Attack Strategy for the Shrinking GeneratorMay 01 2010This work shows that the cryptanalysis of the shrinking generator requires fewer intercepted bits than what indicated by the linear complexity. Indeed, whereas the linear complexity of shrunken sequences is between $A \cdot 2^(S-2)$ and $A \cdot 2^(S-1)$, ... More
Role of correlations on spin-polarized neutron matterSep 10 2016Using the Hellmann--Feynman theorem we analyze the contribution of the different terms of the nucleon-nucleon interaction to the spin symmetry energy of neutron matter. The analysis is performed within the microscopic Brueckner--Hartree--Fock approach ... More
Illustrating Electric Conductivity Using the Particle-in-a-Box Model: Quantum Superposition is the KeySep 11 2016Most of the textbooks explaining electric conductivity in the context of quantum mechanics provide either incomplete or semi-classical explanations that are not connected with the elementary concepts of quantum mechanics. We illustrate the conduction ... More
Algorithmic Networks: central time to trigger expected emergent open-endednessAug 30 2017Feb 16 2019This article investigates emergence and complexity in complex systems that can share information on a network. To this end, we use a theoretical approach from information theory, computability theory, and complex networks. One key studied question is ... More
New Method for Public Key Distribution Based on Social NetworksMar 11 2015The security of communication in everyday life becomes very important. On the other hand, all existing encryption protocols require from user additional knowledge end resources. In this paper we discuss the problem of public key distribution between interested ... More
Monogamy and ground-state entanglement in highly connected systemsJan 02 2007Nov 29 2007We consider the ground-state entanglement in highly connected many-body systems, consisting of harmonic oscillators and spin-1/2 systems. Varying their degree of connectivity, we investigate the interplay between the enhancement of entanglement, due to ... More
On the thin boundary of the fat attractorFeb 28 2014Dec 15 2016For, $0<\lambda<1$, consider the transformation $T(x) = d x $ (mod 1) on the circle $S^1$, a $C^1$ function $A:S^1 \to \mathbb{R}$, and, the map $F(x,s) = ( T(x) , \lambda \, s + A(x))$, $(x,s)\in S^1 \times \mathbb{R}$. We denote $\mathcal{B}= \mathcal{B}_\lambda$ ... More
Diffeomorphisms with positive metric entropyAug 19 2014Sep 19 2017We obtain a dichotomy for $C^1$-generic, volume-preserving diffeomorphisms: either all the Lyapunov exponents of almost every point vanish or the volume is ergodic and non-uniformly Anosov (i.e. nonuniformly hyperbolic and the splitting into stable and ... More
A simple necessary decoherence condition for a set of historiesJan 21 2004Within the decoherent histories formulation of quantum mechanics, we investigate necessary conditions for decoherence of arbitrarily long histories. We prove that fine-grained histories of arbitrary length decohere for all classical initial states if ... More
Classical predictability and coarse-grained evolution of the quantum baker's mapNov 22 2005We investigate how classical predictability of the coarse-grained evolution of the quantum baker's map depends on the character of the coarse-graining. Our analysis extends earlier work by Brun and Hartle [Phys. Rev. D 60, 123503 (1999)] to the case of ... More
Renormalization for a Class of Dynamical Systems: some Local and Global PropertiesFeb 01 2008We study the period doubling renormalization operator for dynamics which present two coupled laminar regimes with two weakly expanding fixed points. We focus our analysis on the potential point of view, meaning we want to solve $$V=\mathcal{R} (V):=V\circ ... More
Second Phase transition lineAug 05 2016We study the phase transion line of the almost Mathieu operator, that separates arithmetic regions corresponding to singular continuous and a.e. pure point regimes, and prove that both purely singular continuous and a.e. pure point spectrum occur for ... More
Sharp Phase transitions for the almost Mathieu operatorDec 10 2015It is known that the spectral type of the almost Mathieu operator depends in a fundamental way on both the strength of the coupling constant and the arithmetic properties of the frequency. We study the competition between those factors and locate the ... More
Algorithmic Networks: central time to trigger expected emergent open-endednessAug 30 2017Mar 19 2019This article investigates emergence and complexity in complex systems that can share information on a network. To this end, we use a theoretical approach from information theory, computability theory, and complex networks. One key studied question is ... More
Bulk Universality and Clock Spacing of Zeros for Ergodic Jacobi Matrices with A.C. SpectrumOct 18 2008By combining some ideas of Lubinsky with some soft analysis, we prove that universality and clock behavior of zeros for OPRL in the a.c. spectral region is implied by convergence of $\frac{1}{n} K_n(x,x)$ for the diagonal CD kernel and boundedness of ... More
Balancing Straight-Line ProgramsFeb 10 2019Apr 04 2019It is shown that a context-free grammar of size $m$ that produces a single string $w$ (such a grammar is also called a string straight-line program) can be transformed in linear time into a context-free grammar for $w$ of size $\mathcal{O}(m)$, whose ... More
Resilience Analysis for Competing PopulationsMar 14 2019Mar 28 2019Ecological resilience refers to the ability of a system to retain its state when subject to state variables perturbations or parameter changes. While understanding and quantifying resilience is crucial to anticipate the possible regime shifts, characterizing ... More
On the Use of Suffix Arrays for Memory-Efficient Lempel-Ziv Data CompressionMar 25 2009Much research has been devoted to optimizing algorithms of the Lempel-Ziv (LZ) 77 family, both in terms of speed and memory requirements. Binary search trees and suffix trees (ST) are data structures that have been often used for this purpose, as they ... More
Perturbations of the Lambda-CDM model in a dynamical systems perspectiveApr 04 2019The observational success and simplicity of the $\Lambda$CDM model, and the explicit analytic perturbations thereof, set the standard for any alternative cosmology. It therefore serves as a comparison ground and as a test case for methods which can be ... More
Demonstratio insignis theorematis numerici circa uncias potestatum binomialiumJan 31 2012This paper is about the product z^q/(1 - z)^(q + 1)(1 + (z/(1 - z)))^p, Euler gives the Talylor-Series and takes a closer look at the coefficient.
Variae considerationes circa series hypergeometricasJan 31 2012Euler gives an asymptotic approximation for the function f(x) and recognizes that he is trying to interpolate the factorial function introduced in E19 "De progressionibus transcendentibus seu quarum termini generales algebraice dari nequeunt". The paper ... More
Theorematum quorundam arithmeticorum demonstrationesFeb 16 2012Euler proves that the sum of two 4th powers can't be a 4th power and that the difference of two distinct non-zero 4th powers can't be a 4th power and Fermat's theorem that the equation x(x+1)/2=y^4 can only be solved in integers if x=1 and the final theorem ... More
High momentum components in the nuclear symmetry energyNov 03 2011Jan 04 2012The short-range and tensor correlations associated to realistic nucleon-nucleon interactions induce a population of high-momentum components in the many-body nuclear wave function. We study the impact of such high-momentum components on bulk observables ... More
Livsic theorem for diffeomorphism cocyclesNov 06 2017May 06 2018We prove the so called Liv\v{s}ic theorem for cocycles taking values in the group of $C^{1+\beta}-diffeomorphisms of any closed manifold of arbitrary dimension. Since no localization hypothesis is assumed, this result is completely global in the space ... More
Density of Yang-Lee zeros in the thermodynamic limit from tensor network methodsAug 31 2015The distribution of Yang-Lee zeros in the ferromagnetic Ising model in both two and three dimensions is studied on the complex field plane directly in the thermodynamic limit via the tensor network methods. The partition function is represented as a contraction ... More
Symplectomorphisms with positive metric entropyApr 01 2019We obtain a dichotomy for $C^1$-generic symplectomorphisms: either all the Lyapunov exponents of almost every point vanish, or the map is partially hyperbolic and ergodic with respect to volume. This completes a program first put forth by Ricardo Ma\~n\'e. ... More
Tight Hardness Results for Maximum Weight RectanglesFeb 18 2016Mar 03 2016Given $n$ weighted points (positive or negative) in $d$ dimensions, what is the axis-aligned box which maximizes the total weight of the points it contains? The best known algorithm for this problem is based on a reduction to a related problem, the Weighted ... More
Universal Algorithm for Optimal Estimation of Quantum States from Finite EnsemblesJul 14 1997Jul 16 1997We present a universal algorithm for the optimal quantum state estimation of an arbitrary finite dimensional system. The algorithm specifies a physically realizable positive operator valued measurement (POVM) on a finite number of identically prepared ... More
Mimetic Spectral Element advectionApr 25 2013We present a discretization of the linear advection of differential forms on bounded domains. The framework previously established is extended to incorporate the Lie derivative, $\mathcal L$, by means of Cartan's homotopy formula. The method is based ... More
Sum rules of single-particle spectral functions in hot asymmetric nuclear matterJul 25 2005The neutron and proton single-particle spectral functions in asymmetric nuclear matter fulfill energy weighted sum rules. The validity of these sum rules within the self-consistent Green's function approach is investigated. The various contributions to ... More
Time and Memory Efficient Lempel-Ziv Compression Using Suffix ArraysDec 30 2009The well-known dictionary-based algorithms of the Lempel-Ziv (LZ) 77 family are the basis of several universal lossless compression techniques. These algorithms are asymmetric regarding encoding/decoding time and memory requirements, with the former being ... More