306 citations
Counting papers with at most 25 authors, so collaboration author lists do not stand in for the people here.
- Universidade do PortoPT174 papers
- University of CoimbraPT98 papers
- University of MinhoPT81 papers
- University of LisbonPT24 papers
- Centre National de la Recherche ScientifiqueFR22 papers
- Instituto Superior TécnicoPT22 papers
- UCLouvainBE13 papers
- Universidade Federal da BahiaBR13 papers
- Centro de Análise Matemática Geometria e Sistemas DinâmicosPT10 papers
- Pontifícia Universidade Católica do Rio de JaneiroBR10 papers
- Universidad de La LagunaES9 papers
- Universidade Federal do Rio de JaneiroBR9 papers
21 papers · 1 filter
Covariant Lie derivatives and Frölicher-Nijenhuis bracket on Lie Algebroids
Antonio De Nicola, Ivan Yudin
We define covariant Lie derivatives acting on vector-valued forms on Lie algebroids and study their properties. This allows us to obtain a concise formula for the Frölicher-Nijenhu…
Equations over free inverse monoids with idempotent variables
Volker Diekert, Florent Martin, Geraud Senizergues +1
We introduce the notion of idempotent variables for studying equations in inverse monoids. It is proved that it is decidable in singly exponential time (DEXPTIME) whether a system…
The congruence on semigroups
M. H. Shahzamanian
In this paper we define a congruence on semigroups. For the finite semigroups , is the smallest congruence relation such that is a nilpotent s…
Sampling local properties of attractors via Extreme Value Theory
Davide Faranda, Jorge Milhazes Freitas, Pierre Guiraud +1
We provide formulas to compute the coefficients entering the affine scaling needed to get a non-degenerate function for the asymptotic distribution of the maxima of some kind of ob…
McCammond's normal forms for free aperiodic semigroups revisited
Jorge Almeida, José Carlos Costa, Marc Zeitoun
This paper revisits the solution of the word problem for -terms interpreted over finite aperiodic semigroups, obtained by J. McCammond. The original proof of correctness of McCa…
Cosymplectic p-spheres
Beniamino Cappelletti-Montano, Antonio De Nicola, Ivan Yudin
We introduce cosymplectic circles and cosymplectic spheres, which are the analogues in the cosymplectic setting of contact circles and contact spheres. We provide a complete classi…
Absorption of scalars by nonextremal charged black holes in string theory
Filipe Moura
We analyze the low frequency absorption cross section of minimally coupled massless scalar fields by different kinds of charged static black holes in string theory, namely the D1-D…
Virial theorem in quasi-coordinates and Lie algebroid formalism
José F. Cariñena, Irina Gheorghiu, Eduardo Martínez +1
In this paper, the geometric approach to the virial theorem developed in \cite{CFR12} is written in terms of quasi-velocities (see \cite{CNCS07}). A generalization of the virial th…
Geometric characterizations of virtually free groups
Vítor Araújo, Pedro V. Silva
Four geometric conditions on a geodesic metric space, which are stronger variants of classical conditions characterizing hyperbolicity, are proved to be equivalent. In the particul…
Hölder conditions for endomorphisms of hyperbolic groups
Vítor Araújo, Pedro V. Silva
It is proved that an endomorphism of a hyperbolic group satisfies a Hölder condition with respect to a visual metric if and only if is virtually injective and is a…
Sasakian nilmanifolds
Beniamino Cappelletti-Montano, Antonio De Nicola, Juan Carlos Marrero +1
We prove that a compact nilmanifold admits a Sasakian structure if and only if it is a compact quotient of the generalized Heisenberg group of odd dimension by a co-compact discret…
Relative category and monoidal topological complexity
J. G. Carrasquel-Vera, J. M. García Calcines, L. Vandembroucq
If a map has a homotopy retraction, then Doeraene and El Haouari conjectured that the sectional category and the relative category of are the same. In this work we discuss…
Finiteness results for subgroups of finite extensions
Vitor Araujo, Pedro V. Silva, Mihalis Sykiotis
We discuss in the context of finite extensions two classical theorems of Takahasi and Howson on subgroups of free groups. We provide bounds for the rank of the intersection of subg…
Zeros of orthogonal polynomials generated by the Geronimus perturbation of measures
Amílcar Branquinho, Edmundo J. Huertas, Fernando R. Rafaeli
This paper deals with monic orthogonal polynomial sequences (MOPS in short) generated by a Geronimus canonical spectral transformation of a positive Borel measure , i.e., \begin…
3/4 Fractional superdiffusion of energy in a system of harmonic oscillators perturbed by a conservative noise
Cedric Bernardin, Patricia Gonçalves, Milton Jara
We consider a harmonic chain perturbed by an energy conserving noise and show that after a space-time rescaling the energy-energy correlation function is given by the solution of a…
On linearly related sequences of difference derivatives of discrete orthogonal polynomials
R. Alvarez-Nodarse, J. Petronilho, N. C. Pinzon-Cortes +1
Let D_v the difference operator and q-difference operators defined by D_ωp(x) = \frac{p(x+ω)-p(x)}ω and D_q p(x) = \frac{p(qx)-p(x)}{(q-1)x}, respectively. Let U and V be two momen…
Generic area-preserving reversible diffeomorphisms
Mário Bessa, Maria Carvalho, Alexandre Rodrigues
Let M be a surface and R an involution in M whose set of fixed points is a submanifold with dimension 1 and such that R is an isometry. We will show that there is a residual subset…
Further remarks on the "Smith is Huq" condition
Nelson Martins-Ferreira, Tim Van der Linden
We compare the 'Smith is Huq' condition (SH) with three commutator conditions in semi-abelian categories: first an apparently weaker condition which arose in joint work with Bourn…
Algebraic and combinatorial rank of divisors on finite graphs
Lucia Caporaso, Yoav Len, Margarida Melo
We study the algebraic rank of a divisor on a graph, an invariant defined using divisors on algebraic curves dual to the graph. We prove it satisfies the Riemann-Roch formula, a sp…
Speed of convergence for laws of rare events and escape rates
Ana Cristina Moreira Freitas, Jorge Milhazes Freitas, Mike Todd
We obtain error terms on the rate of convergence to Extreme Value Laws for a general class of weakly dependent stochastic processes. The dependence of the error terms on the `time'…
Stability in simple heteroclinic networks in
Sofia B. S. D. Castro, Alexander Lohse
We describe all heteroclinic networks in made of simple heteroclinic cycles of types or , with at least one common connecting trajectory. For networks made of…