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Early evolution of disrupted asteroid P/2016 G1 (PANSTARRS)Jul 12 2016We present deep imaging observations of activated asteroid P/2016 G1 (PANSTARRS) using the 10.4m Gran Telescopio Canarias (GTC) from late April to early June 2016. The images are best interpreted as the result of a relatively short-duration event with ... More

Comet 22P/Kopff: Dust environment and grain ejection anisotropy from visible and infrared observationsApr 18 2012We present optical observations and Monte Carlo models of the dust coma, tail, and trail structures of comet 22P/Kopff during the 2002 and 2009 apparitions. Dust loss rates, ejection velocities, and power-law size distribution functions are derived as ... More

Dust Properties of Multi-Tailed Active Asteroid (6478) GaultMar 24 2019Aims. To investigate the grain properties of the dust ejected from asteroid (6478) Gault and give insight into the activity mechanism(s). Methods. We used a Monte Carlo dust tail brightness code to retrieve the dates of dust ejection, the physical properties ... More

A direct proof of the Brunn-Minkowski inequality in Nilpotent Lie groupsApr 29 2019The purpose of this work is to give a direct proof of the multiplicative Brunn-Minkowski inequality in nilpotent Lie groups based on Hadwiger-Ohmann's one of the classical Brunn-Minkowski inequality in Euclidean space.

Lateral downflows in sunspot penumbral filaments and their temporal evolutionFeb 10 2015Apr 10 2015We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe I 617.3 nm line taken ... More

The dark side of penumbral microjets: Observations in HαMay 03 2019We present data of 10 penumbral microjets (PMJs) observed in H\alpha, Ca II 8542 \AA, and Fe I 6302 \AA line pair with the Swedish 1 m Solar Telescope (SST) with CRISP and Ca II K with SST/CHROMIS in active region NOAA 12599 on the 12th October 2016 at ... More

A note on the Gauss map of complete nonorientable minimal surfacesDec 22 1998We construct complete nonorientable minimal surfaces whose Gauss map omits two points of the projective plane. This result proves that Fujimoto's theorem is sharp in nonorientable case.

High resolution optical spectroscopy of the $\mathrm{N_2}$-rich comet C/2016 R2 (PanSTARRS)Jan 03 2019Early observations of comet C/2016 R2 (PanSTARRS) have shown that the composition of this comet is very peculiar. We obtained high resolution spectra of the comet in February when it was at 2.8 au from the Sun. We used the UVES spectrograph of the ESO ... More

Exotic Minimal SurfacesApr 15 2010We prove a general fusion theorem for complete orientable minimal surfaces in $\mathbb{R}^3$ with finite total curvature. As a consequence, complete orientable minimal surfaces of weak finite total curvature with exotic geometry are produced. More specifically, ... More

Grassmannian of $k((z))$: Picard Group, Equations and AutomorphismsJan 30 1998This paper aims at generalizing some geometric properties of Grassmannians of finite dimensional vector spaces to the case of Grassmannnians of infinite dimensional ones, in particular for that of $k((z))$. It is shown that the Determinant Line Bundle ... More

Bounded, minimal, and short representations of unit interval and unit circular-arc graphsAug 14 2014Oct 08 2014We consider the unrestricted, minimal, and bounded representation problems for unit interval (UIG) and unit circular-arc (UCA) graphs. In the unrestricted version, a proper circular-arc (PCA) model $\cal M$ is given and the goal is to obtain an equivalent ... More

Non-standard quantum so(3,2) and its contractionsApr 07 1997A full (triangular) quantum deformation of so(3,2) is presented by considering this algebra as the conformal algebra of the 2+1 dimensional Minkowskian spacetime. Non-relativistic contractions are analysed and used to obtain quantum Hopf structures for ... More

A certifying and dynamic algorithm for the recognition of proper circular-arc graphsSep 19 2015We present a dynamic algorithm for the recognition of proper circular-arc (PCA) graphs, that supports the insertion and removal of vertices (together with its incident edges). The main feature of the algorithm is that it outputs a minimally non-PCA induced ... More

Fully dynamic recognition of proper circular-arc graphsNov 15 2011We present a fully dynamic algorithm for the recognition of proper circular-arc (PCA) graphs. The allowed operations on the graph involve the insertion and removal of vertices (together with its incident edges) or edges. Edge operations cost O(log n) ... More

Uniform Approximation by Complete Minimal Surfaces of Finite Total Curvature in $\mathbb{R}^3$Mar 18 2009Jun 04 2012An approximation theorem for minimal surfaces by complete minimal surfaces of finite total curvature in $\mathbb{R}^3$ is obtained. This Mergelyan type result can be extended to the family of complete minimal surfaces of weak finite total curvature, that ... More

Independence of the metric in the fine $C^0$-topology of a function spaceJan 16 2014We prove that, for any topological space $X$ and any metric space $(Y,d)$, the fine topology on the space of continuous functions from $X$ into $Y$ is independent of the metric $d$.

Generalized KP Hierarchy for Several VariablesAug 01 2000Following the techniques of M. Sato (see \cite{Sa}), a generalization of the KP hierarchy for more than one variable is proposed. An approach to the classification of solutions and a method to construct algebraic solutions is also offered.

Total 2-domination of proper interval graphsDec 03 2018A set of vertices $W$ of a graph $G$ is a total $k$-dominating set when every vertex of $G$ has at least $k$ neighbors in $W$. In a recent article, Chiarelli et al.\ (Improved Algorithms for $k$-Domination and Total $k$-Domination in Proper Interval Graphs, ... More

A Note On Polar RepresentationsApr 11 2017We show how to determine a possibly reducible polar representation of a compact connected Lie group G from its history and dimension.

Representations of Compact Lie Groups of Low CohomogeneityFeb 08 2018We survey different tools to classify representations of compact Lie groups according to their cohomogeneity and apply these methods to the case of irreducible representations of cohomogeneity 6, 7 and 8.

Arithmetic infinite Grassmannians and the induced central extensionsOct 02 2008The construction of families of Sato Grassmannians, their determinant line bundles and the extensions induced by them are given. The base scheme is an arbitrary scheme.

On a local Fourier analysis for overlapping block smoothers on triangular gridsOct 14 2015A general local Fourier analysis for overlapping block smoothers on triangular grids is presented. This analysis is explained in a general form for its application to problems with different discretizations. This tool is demonstrated for two different ... More

2+1 Kinematical expansions: from Galilei to de Sitter algebrasFeb 03 1999Expansions of Lie algebras are the opposite process of contractions. Starting from a Lie algebra, the expansion process goes to another one, non-isomorphic and less abelian. We propose an expansion method based in the Casimir invariants of the initial ... More

The family of quaternionic quasi-unitary Lie algebras and their central extensionsNov 13 1998The family of quaternionic quasi-unitary (or quaternionic unitary Cayley--Klein algebras) is described in a unified setting. This family includes the simple algebras sp(N+1) and sp(p,q) in the Cartan series C_{N+1}, as well as many non-semisimple real ... More

"Cayley-Klein" schemes for real Lie algebras and Freudhental Magic SquaresFeb 24 1997We introduce three "Cayley-Klein" families of Lie algebras through realizations in terms of either real, complex or quaternionic matrices. Each family includes simple as well as some limiting quasi-simple real Lie algebras. Their relationships naturally ... More

Homogeneous phase spaces: the Cayley-Klein frameworkFeb 24 1997The metric structure of homogeneous spaces of rank-one and rank-two associated to the real pseudo-orthogonal groups SO(p,q) and some of their contractions (e.g., ISO(p,q), Newton-Hooke type groups...) is studied. All these spaces are described from a ... More

Dissecting the Spatial Structure of Cities from Human Mobility Patterns to Define Functional Urban BoundariesSep 20 2017Since the industrial revolution, accelerated urban growth has overflown administrative divisions, merged cities into large built extensions, and blurred the boundaries between urban and rural land-uses. These traits, present in most of contemporary metropolis, ... More

On the asymptotic nature of first order mean field gamesMar 08 2019For a class of finite horizon first order mean field games and associated N-player games, we give a simple proof of convergence of symmetric N-player Nash equilibria in distributed open-loop strategies to solutions of the mean field game in Lagrangian ... More

On spacelike surfaces in 4-dimensional Lorentz-Minkowski spacetime through a lightconeFeb 21 2012On any spacelike surface in a lightcone of four dimensional Lorentz-Minkowski space a distinguished smooth function is considered. It is shown how both extrinsic and intrinsic geometry of such a surface is codified by this function. The existence of a ... More

The families of orthogonal, unitary and quaternionic unitary Cayley--Klein algebras and their central extensionsJul 26 1999The families of quasi-simple or Cayley--Klein algebras associated to antihermitian matrices over R, C and H are described in a unified framework. These three families include simple and non-simple real Lie algebras which can be obtained by contracting ... More

Minimal surfaces in $\mathbb{R}^3$ properly projecting into $\mathbb{R}^2$Oct 21 2009Jan 12 2012For all open Riemann surface M and real number $\theta \in (0,\pi/4),$ we construct a conformal minimal immersion $X=(X_1,X_2,X_3):M \to \mathbb{R}^3$ such that $X_3+\tan(\theta) |X_1|:M \to \mathbb{R}$ is positive and proper. Furthermore, $X$ can be ... More

Universal integrals for superintegrable systems on N-dimensional spaces of constant curvatureOct 17 2006An infinite family of classical superintegrable Hamiltonians defined on the N-dimensional spherical, Euclidean and hyperbolic spaces are shown to have a common set of (2N-3) functionally independent constants of the motion. Among them, two different subsets ... More

Minimal and minimum unit circular-arc modelsSep 05 2016Oct 09 2017A proper circular-arc (PCA) model is a pair ${\cal M} = (C, \cal A)$ where $C$ is a circle and $\cal A$ is a family of inclusion-free arcs on $C$ in which no two arcs of $\cal A$ cover $C$. A PCA model $\cal U = (C,\cal A)$ is a $(c, \ell)$-CA model when ... More

Magnetically driven quantum heat engineMay 12 2014We studied the efficiency of two different schemes for a magnetically driven quantum heat engine, by considering as the working substance a single nonrelativistic particle trapped in a cylindrical potential well, in the presence of an external magnetic ... More

Compact spacelike surfaces in four-dimensional Lorentz-Minkowski spacetime with a non-degenerate lightlike normal directionApr 21 2016A spacelike surface in four-dimensional Lorentz-Minkowski spacetime through the lightcone has a meaningful lightlike normal vector field $\eta$. Several sufficient assumptions on such a surface with non-degenerate $\eta$-second fundamental form are established ... More

Thermodynamics of the Relativistic Fermi gas in D DimensionsJul 27 2014The influence of spatial dimensionality and particle-antiparticle pair production on the thermodynamic properties of the relativistic Fermi gas, at finite chemical potential, is studied. Resembling a kind of phase transition, qualitatively different behaviors ... More

A Conversation with George G. RoussasApr 13 2011George G. Roussas was born in the city of Marmara in central Greece, on June 29, 1933. He received a B.A. with high honors in Mathematics from the University of Athens in 1956, and a Ph.D. in Statistics from the University of California, Berkeley, in ... More

On Convergence Properties of Shannon EntropyOct 05 2007Convergence properties of Shannon Entropy are studied. In the differential setting, it is shown that weak convergence of probability measures, or convergence in distribution, is not enough for convergence of the associated differential entropies. A general ... More

On the First eigenvalue of the Laplace operator for Compact Spacelike submanifolds in Lorentz-Minkowski Spacetime $\mathbb{L}^{m}$Dec 04 2018Feb 11 2019By means of a family of counter-examples, it is shown that the Reilly upper bound for the first eigenvalue of the Laplace operator for a compact submanifold in Euclidean space does not work for $n$-dimensional compact spacelike submanifolds of Lorentz-Minkowski ... More

A new Lie algebra expansion method: Galilei expansions to Poincare and Newton-HookeSep 02 1999Oct 09 2000We modify a Lie algebra expansion method recently introduced for the (2+1)-dimensional kinematical algebras so as to work for higher dimensions. This new improved and geometrical procedure is applied to expanding the (3+1)-dimensional Galilei algebra ... More

Deep convolutional recurrent autoencoders for learning low-dimensional feature dynamics of fluid systemsAug 03 2018Aug 22 2018Model reduction of high-dimensional dynamical systems alleviates computational burdens faced in various tasks from design optimization to model predictive control. One popular model reduction approach is based on projecting the governing equations onto ... More

Multigrid waveform relaxation for the time-fractional heat equationAug 18 2016Aug 24 2017In this work, we propose an efficient and robust multigrid method for solving the time-fractional heat equation. Due to the nonlocal property of fractional differential operators, numerical methods usually generate systems of equations for which the coefficient ... More

Chaos-Based Anytime Reliable Coded CommunicationsApr 17 2019Anytime reliable communication systems are needed in contexts where the property of vanishing error probability with time is critical. This is the case of unstable real time systems that are to be controlled through the transmission and processing of ... More

Nonorientable maximal surfaces in the Lorentz-Minkowski 3-spaceMay 13 2009Feb 12 2010The geometry and topology of complete nonorientable maximal surfaces with lightlike singularities in the Lorentz-Minkowski 3-space are studied. Some topological congruence formulae for surfaces of this kind are obtained. As a consequence, some existence ... More

Magneto-strain-driven quantum engine on a graphene flakeMay 15 2015We propose a novel conceptual design for a graphene-based quantum engine, driven by a superposition of mechanical strain and an external magnetic field. Engineering of strain in a nanoscale graphene flake creates a gauge field with an associated uniform ... More

A fully-discrete scheme for systems of nonlinear Fokker-Planck-Kolmogorov equationsNov 28 2017May 02 2018We consider a system of Fokker-Planck-Kolmogorov (FPK) equations, where the dependence of the coefficients is nonlinear and nonlocal in time with respect to the unknowns. We extend the numerical scheme proposed and studied recently by the authors for ... More

Hard thermal loops in long wave-length and static external gravitational fieldsJan 10 2013We study, in the long wave-length and static limits, the structure of the n-point graviton functions at high temperature. Using the gauge and Weyl invariance of the theory, we derive a simple expression for the hard thermal amplitudes in these two limits. ... More

Interpolation of operators when the extreme spaces are $L^\infty$Apr 29 1991In this paper, equivalence between interpolation properties of linear operators and monotonicity conditions are studied, for a pair $(X_0,X_1)$ of rearrangement invariant quasi Banach spaces, when the extreme spaces of the interpolation are $L^\infty$ ... More

Proper holomorphic embeddings of Riemann surfaces with arbitrary topology into $\mathbb{C}^2$Apr 11 2011We prove that given an open Riemann surface $N,$ there exists an open domain $M\subset N$ homeomorphic to $N$ which properly holomorphically embeds in $\mathbb{C}^2.$ Furthermore, $M$ can be chosen with hyperbolic conformal type. In particular, any open ... More

On the Relationship between Mutual Information and Minimum Mean-Square Errors in Stochastic Dynamical SystemsOct 05 2007We consider a general stochastic input-output dynamical system with output evolving in time as the solution to a functional coefficients, It\^{o}'s stochastic differential equation, excited by an input process. This general class of stochastic systems ... More

CPT Violation in $\boldsymbol{B^0_s}$--$\boldsymbol{\bar B^0_s}$ mixing and the measurement of CP Violation in $\boldsymbol{B_s\to K^+K^-}$Mar 11 2019A simple analysis of time-dependent $B_s\to K^+K^-$ transitions, based on recent results from the LHCb experiment, is presented. The benefits of adopting a fully consistent theoretical description of the $B^0_s$--$\bar B^0_s$ mixing are stressed. It is ... More

The uniqueness of the helicoid in the Lorentz-Minkowski space L3Jul 13 2007Dec 04 2007In this paper we deal with the uniqueness of the Lorentzian helicoid and Enneper's surface among properly embedded maximal surfaces with lightlike boundary of mirror symmetry in the Lorentz-Minkowski space L3.

Geometries of orthogonal groups and their contractions: a unified classical deformation viewpointOct 23 1996The geometries of spaces having as groups the real orthogonal groups and some of their contractions are described from a common point of view. Their central extensions and Casimirs are explicitly given. An approach to the trigonometry of their spaces ... More

Representations with $Sp(1)^k$-reductions and quaternion-Kähler symmetric spacesFeb 24 2017We classify non-polar irreducible representations of connected compact Lie groups whose orbit space is isometric to that of a representation of a finite extension of $Sp(1)^k$ for some $k>0$. It follows that they are obtained from isotropy representations ... More

Relative parabolicity of zero mean curvature surfaces in $R^3$ and $R_1^3$Oct 20 2004If the Lorentzian norm on a maximal surface in the 3-dimensional Lorentz-Minkowski space $R_1^3$ is positive and proper, then the surface is relative parabolic. As a consequence, entire maximal graphs with a closed set of isolated singularities are relative ... More

The Kepler problem on 3D spaces of variable and constant curvature from quantum algebrasApr 05 2006A quantum sl(2,R) coalgebra (with deformation parameter z) is shown to underly the construction of superintegrable Kepler potentials on 3D spaces of variable and constant curvature, that include the classical spherical, hyperbolic and (anti-)de Sitter ... More

Superintegrability on Three-Dimensional Riemannian and Relativistic Spaces of Constant CurvatureDec 23 2005Jan 27 2006A family of classical superintegrable Hamiltonians, depending on an arbitrary radial function, which are defined on the 3D spherical, Euclidean and hyperbolic spaces as well as on the (2+1)D anti-de Sitter, Minkowskian and de Sitter spacetimes is constructed. ... More

Metric regularity under Gâteaux differentiability with applications to optimization and stochastic optimal control problemsOct 27 2018The main objective of this work is to study the existence of Lagrange multipliers for infinite dimensional problems under G\^ateux differentiability assumptions on the data. Our investigation follows two main steps: the proof of the existence of Lagrange ... More

A new class of plastic flow evolution equations for anisotropic multiplicative elastoplasticity based on the notion of a corrector elastic strain rateDec 31 2016In this paper we present a new general framework for anisotropic elastoplasticity at large strains. The new framework presents the following characteristics: (1) It is valid for non-moderate large strains, (2) it is valid for both elastic and plastic ... More

(Anti)de Sitter/Poincare symmetries and representations from Poincare/Galilei through a classical deformation approachDec 19 2006Dec 12 2007A classical deformation procedure, based on universal enveloping algebras, Casimirs and curvatures of symmetrical homogeneous spaces, is applied to several cases of physical relevance. Starting from the (3+1)D Galilei algebra, we describe at the level ... More

Conformal compactification and cycle-preserving symmetries of spacetimesOct 17 2001The cycle-preserving symmetries for the nine two-dimensional real spaces of constant curvature are collectively obtained within a Cayley-Klein framework. This approach affords a unified and global study of the conformal structure of the three classical ... More

Casimir invariants for the complete family of quasi-simple orthogonal algebrasFeb 24 1997A complete choice of generators of the center of the enveloping algebras of real quasi-simple Lie algebras of orthogonal type, for arbitrary dimension, is obtained in a unified setting. The results simultaneously include the well known polynomial invariants ... More

The eternal dominating set problem for interval graphsAug 29 2018We prove that, in games in which all the guards move at the same turn, the eternal domination and the clique-connected cover numbers coincide for interval graphs. A linear algorithm for the eternal dominating set problem is obtained as a by-product.

Hereditary biclique-Helly graphs: recognition and maximal biclique enumerationMar 09 2011A biclique is a set of vertices that induce a bipartite complete graph. A graph G is biclique-Helly when its family of maximal bicliques satisfies the Helly property. If every induced subgraph of G is also biclique-Helly, then G is hereditary biclique-Helly. ... More

Null Curves in $\mathbb{C}^3$ and Calabi-Yau ConjecturesDec 15 2009Jan 20 2012For any open orientable surface $M$ and convex domain $\Omega\subset \mathbb{C}^3,$ there exists a Riemann surface $N$ homeomorphic to $M$ and a complete proper null curve $F:N\to\Omega.$ This result follows from a general existence theorem with many ... More

Periodic Maximal surfaces in the Lorentz-Minkowski space $ł^3$Dec 22 2004Jan 17 2005A maximal surface $\sb$ with isolated singularities in a complete flat Lorentzian 3-manifold $\N$ is said to be entire if it lifts to a (periodic) entire multigraph $\tilde{\sb}$ in $\l^3.$ In addition, $\sb$ is called of finite type if it has finite ... More

On the discretization of some nonlinear Fokker-Planck-Kolmogorov equations and applicationsAug 07 2017Jan 02 2018In this work, we consider the discretization of some nonlinear Fokker-Planck-Kolmogorov equations. The scheme we propose preserves the non-negativity of the solution, conserves the mass and, as the discretization parameters tend to zero, has limit measure-valued ... More

Compact complete null curves in Complex 3-spaceJun 03 2011Jun 27 2011We prove that for any open orientable surface $S$ of finite topology, there exist a Riemann surface $\mathcal{M},$ a relatively compact domain $M\subset\mathcal{M}$ and a continuous map $X:\bar{M}\to\mathbb{C}^3$ such that: $\mathcal{M}$ and $M$ are homeomorphic ... More

Relationship between the field local quadrature and the quantum discord of a photon-added correlated channel under the influence of scattering and phase fluctuation noiseAug 20 2017We study quantum correlations and discord in a bipartite continuous variable hybrid system formed by linear combinations of coherent states $|\alpha\rangle$ and single photon added coherent states (SPACS) of the form $|\psi\rangle_{\text{dp(pa)}}= \mathcal{N}/\sqrt{2} ... More

Extraordinary sound screening in perforated platesApr 17 2008We report extraordinary effects in the transmission of sound through periodically perforated plates, supported by both measurements and theory. In agreement with recent observations in slit arrays [M. H. Lu et al. Phys. Rev. Lett. 99, 174301 (2007)], ... More

Qatar Exoplanet Survey: Qatar-8b, 9b and 10b --- A Hot Saturn and Two Hot JupitersMar 20 2019May 10 2019In this paper we present three new extrasolar planets from the Qatar Exoplanet Survey (QES). Qatar-8b is a hot Saturn, with Mpl = 0.37 Mjup and Rpl = 1.3 Rjup, orbiting a solar-like star every Porb = 3.7 days. Qatar-9b is a hot Jupiter with a mass of ... More

Dust Properties of Double-Tailed Active Asteroid (6478) GaultMar 24 2019Apr 12 2019Asteroid (6478) Gault was discovered to exhibit a comet-like tail in observations from December 2018, becoming a new member of the so-called active asteroid population in the main asteroid belt. The aims are to investigate the grain properties of the ... More

Resolution of complex fluorescence spectra of lipids and nicotinic acetylcholine receptor by multivariate analysis reveals protein-mediated effects on the receptor's immediate lipid microenvironmentFeb 18 2009Analysis of fluorescent spectra from complex biological systems containing various fluorescent probes with overlapping emission bands is a challenging task. Valuable information can be extracted from the full spectra, however, by using multivariate analysis ... More

Qatar Exoplanet Survey: Qatar-8b, 9b and 10b --- A Hot Saturn and Two Hot JupitersMar 20 2019In this paper we present three new extrasolar planets from the Qatar Exoplanet Survey (QES). Qatar-8b is a hot Saturn, with Mpl = 0.37 Mjup and Rpl = 1.3 Rjup, orbiting a solar-like star every Porb = 3.7 days. Qatar-9b is a hot Jupiter with a mass of ... More

Qatar Exoplanet Survey: Qatar-8b, 9b and 10b --- A Hot Saturn and Two Hot JupitersMar 20 2019Apr 15 2019In this paper we present three new extrasolar planets from the Qatar Exoplanet Survey (QES). Qatar-8b is a hot Saturn, with Mpl = 0.37 Mjup and Rpl = 1.3 Rjup, orbiting a solar-like star every Porb = 3.7 days. Qatar-9b is a hot Jupiter with a mass of ... More

The splitting of double-component active asteroid P/2016 J1 (PANSTARRS)Feb 13 2017We present deep imaging observations, orbital dynamics, and dust tail model analyses of the double-component asteroid P/2016 J1 (J1-A and J1-B). The observations were acquired at the Gran Telescopio Canarias (GTC) and the Canada-France-Hawaii Telescope ... More

Learning Convex Partitions and Computing Game-theoretic Equilibria from Best Response QueriesJul 17 2018Apr 09 2019Suppose that an $m$-simplex is partitioned into $n$ convex regions having disjoint interiors and distinct labels, and we may learn the label of any point by querying it. The learning objective is to know, for any point in the simplex, a label that occurs ... More

Classification of quadruple Galois canonical covers IFeb 05 2003Dec 08 2003In this article we classify quadruple Galois canonical covers of smooth surfaces of minimal degree. The classification shows that they are either non-simple cyclic covers or bi-double covers. If they are bi-double then they are all fiber products of double ... More

Mok's characteristic varieties and the normal holonomy groupMar 06 2015May 23 2017In this paper we complete the study of the normal holonomy groups of complex submanifolds (non nec. complete) of Cn or CPn. We show that irreducible but non transitive normal holonomies are exactly the Hermitian s-representations of [CD09, Table 1] (see ... More

On the Integrability of the Geodesic Flow on a Friedmann-Robertson-Walker SpacetimeDec 24 2017Dec 21 2018We study the geodesic flow on the cotangent bundle of a Friedman-Robertson-Walker spacetime (M, g). On this bundle, the HamiltonJacobi equation is completely separable and this separability leads us to construct four linearly independent integrals in ... More

Global convergence of a non-convex Douglas-Rachford iterationMar 12 2012Nov 27 2014We establish a region of convergence for the proto-typical non-convex Douglas-Rachford iteration which finds a point on the intersection of a line and a circle. Previous work on the non-convex iteration [2] was only able to establish local convergence, ... More

Analytic solution for electrons and holes in graphene under electromagnetic radiation: gap appearance and non-linear current effectsSep 24 2008Jan 05 2009We find the exact solution of graphene s carriers under electromagnetic radiation. To obtain such solution, we combine Floquet theory with a trial solution. Then the energy spectrum is obtained without using any approximation. Using such results, we prove ... More

Trigonometry of spacetimes: a new self-dual approach to a curvature/signature (in)dependent trigonometryOct 26 1999A new method to obtain trigonometry for the real spaces of constant curvature and metric of any (even degenerate) signature is presented. The method encapsulates trigonometry for all these spaces into a single basic trigonometric group equation. This ... More

Complete minimal surfaces and harmonic functionsOct 22 2009We prove that for any open Riemann surface $M$ and any non constant harmonic function $h:M \to \mathbb{R},$ there exists a complete conformal minimal immersion $X:M \to \mathbb{R}^3$ whose third coordinate function coincides with $h.$ As a consequence, ... More

Virasoro and KdVFeb 02 2016We investigate the structure of representations of the (positive half of the) Virasoro algebra and situations in which they decompose as a tensor product of Lie algebra representations. As an illustration, we apply these results to the differential operators ... More

On polynomials associated with an Uvarov modification of a quartic potential Freud-like weightMay 06 2015Jan 19 2016In this contribution we consider sequences of monic polynomials orthogonal with respect to the standard Freud-like inner product involving a quartic potential $\left\langle p,q\right\rangle_{M}=\int_{\mathbb{R}}p(x)q(x)e^{-x^{4}+2tx^{2}}dx+Mp(0)q(0).$ ... More

An a posteriori error analysis of an elliptic optimal control problem in measure spaceJun 13 2018We propose an a posteriori error estimator for a sparse optimal control problem: the control variable lies in the space of regular Borel measures. We consider a solution technique that relies on the discretization of the control variable as a linear combination ... More

The moduli space of embedded singly periodic maximal surfaces with isolated singularities in the Lorentz-Minkowski space $ł^3$Dec 09 2004We show that, up to some natural normalizations, the moduli space of singly periodic complete embedded maximal surfaces in the Lorentz-Minkowski space $\l^3=(\r^3,dx_1^2+dx_2^2-dx_3^2),$ with fundamental piece having a finite number $(n+1)$ of singularities, ... More

The space of complete embedded maximal surfaces with isolated singularities in the 3-dimensional Lorentz-Minkowski space $ł^3$Nov 19 2003Jan 27 2005We show that a complete embedded maximal surface in the 3-dimensional Lorentz-Minkowski space $L^3$ with a finite number of singularities is, up to a Lorentzian isometry, an entire graph over any spacelike plane asymptotic to a vertical half catenoid ... More

Curvature as an integrable deformationMar 22 2019The generalization of (super)integrable Euclidean classical Hamiltonian systems to the two-dimensional sphere and the hyperbolic space by preserving their (super)integrability properties is reviewed. The constant Gaussian curvature of the underlying spaces ... More

The anisotropic oscillator on the two-dimensional sphere and the hyperbolic planeJun 30 2012Feb 08 2013An integrable generalization on the two-dimensional sphere S^2 and the hyperbolic plane H^2 of the Euclidean anisotropic oscillator Hamiltonian with "centrifugal" terms given by $H=1/2(p_1^2+p_2^2)+ \delta q_1^2+(\delta + \Omega)q_2^2 +\frac{\lambda_1}{q_1^2}+\frac{\lambda_2}{q_2^2}$ ... More

Embedded minimal surfaces in $\mathbb{R}^n$Sep 24 2014Dec 15 2015In this paper, we prove that every confomal minimal immersion of an open Riemann surface into $\mathbb{R}^n$ for $n\ge 5$ can be approximated uniformly on compacts by conformal minimal embeddings. Furthermore, we show that every open Riemann surface carries ... More

On the eigenvalues of a class of matrices with displacement structure arising in optimal controlAug 27 2018In this work we present a framework for studying the eigenvalues of a family of matrices with a particular displacement structure. The family admits a specific decomposition as the product of an upper and a lower triangular matrices having an increasing ... More

Assessing Information Transmission in Data Transformations with the Channel Multivariate Entropy TriangleNov 30 2017Oct 10 2018Data transformation, e.g. feature transformation and selection, is an integral part of any machine learning procedure. In this paper we introduce an information-theoretic model and tools to assess the quality of data transformations in machine learning ... More

Spectral stability of traveling fronts for reaction diffusion-degenerate Fisher-KPP equationsJun 15 2016May 31 2017This paper establishes the spectral stability in exponentially weighted spaces of smooth traveling monotone fronts for reaction diffusion equations of Fisher-KPP type with nonlinear degenerate diffusion coefficient. It is assumed that the former is degenerate, ... More

$SU(3) \times SO(10)$ in 6dJul 18 2018Oct 24 2018We discuss a simple and elegant $SU(3)\times SO(10)$ family unified gauge theory in 6d compactified on a torus with the orbifold $T_2/Z_2^3$ and supplemented by a $Z_6\times Z_3$ discrete symmetry. The orbifold boundary conditions generate all the desired ... More

Affine Connections on 3-Sasakian Homogeneous ManifoldsJan 31 2018Jan 28 2019The space of invariant affine connections on every $3$-Sasakian homogeneous manifold of dimension at least $7$ is described. In particular, the remarkable subspaces of invariant affine metric connections, and the subclass with skew-torsion, are also determined. ... More

A curved Henon-Heiles system and its integrable perturbationsMar 31 2015Apr 13 2015The constant curvature analogue on the two-dimensional sphere and the hyperbolic space of the integrable H\'enon-Heiles Hamiltonian $\mathcal{H}$ given by $$ \mathcal{H}=\dfrac{1}{2}(p_{1}^{2}+p_{2}^{2})+ \Omega \left(q_{1}^{2}+ 4 q_{2}^{2}\right) +\alpha ... More

On quantum deformations of (anti-)de Sitter algebras in (2+1) dimensionsFeb 04 2013Aug 04 2013Quantum deformations of (anti-)de Sitter algebras in (2+1) dimensions are revisited, and several features of these quantum structures are reviewed. In particular, the classification problem of (2+1) (A)dS Lie bialgebras is presented and the associated ... More

Bohr-Fourier series on solenoids via its transversal variationMar 01 2019The Bohr-Fourier series development on one dimensional solenoids is analyzed by using invariant functions and extending Bohr's theory through the study of transversal variation