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
33 papers · 1 filter
Differential identities and polynomial growth of the codimensions
Carla Rizzo, Rafael Bezerra dos Santos, Ana Cristina Vieira
Let be an associative algebra over a field of characteristic zero and let be a Lie algebra over . If acts on by derivations, then such an action determines a…
Influence of intrinsic spin in the formation of singularities for inhomogeneous effective dust space-times
Paulo Luz, Filipe C. Mena, Amir Hadi Ziaie
The evolution of inhomogeneous space-times composed of uncharged fermions is studied for Szekeres metrics which have no Killing vectors, in general. Using the Einstein-Cartan theor…
Gravitational radiation and the evolution of gravitational collapse in cylindrical symmetry
Alfonso García-Parrado, Filipe C. Mena
Using the Sparling form and a geometric construction adapted to spacetimes with a 2-dimensional isometry group, we analyse a quasi-local measure of gravitational energy. We then st…
Multiscale Information Storage of Linear Long-Range Correlated Stochastic Processes
Luca Faes, Margarida Almeida Pereira, Maria Eduarda Silva +4
Information storage, reflecting the capability of a dynamical system to keep predictable information during its evolution over time, is a key element of intrinsic distributed compu…
On the group of a rational maximal bifix code
Jorge Almeida, Alfredo Costa, Revekka Kyriakoglou +1
We give necessary and sufficient conditions for the group of a rational maximal bifix code to be isomorphic with the -group of , when is recurrent and …
Cancellative conjugation semigroups and monoids
A. P. Garrão, N. Martins-Ferreira, M. Raposo +1
We show that the category of cancellative conjugation semigroups is weakly Mal'tsev and give a characterization of all admissible diagrams there. In the category of cancellative co…
Almost complete and equable heteroclinic networks
Peter Ashwin, Sofia Castro, Alexander Lohse
Heteroclinic connections are trajectories that link invariant sets for an autonomous dynamical flow: these connections can robustly form networks between equilibria, for systems wi…
Pseudovarieties of ordered completely regular semigroups
Jorge Almeida, Ondřej Klíma
This paper is a contribution to the theory of finite semigroups and their classification in pseudovarieties, which is motivated by its connections with computer science. The questi…
Clustering indices and decay of correlations in non-Markovian models
Miguel Abadi, Ana Cristina Moreira Freitas, Jorge Milhazes Freitas
When there is no independence, abnormal observations may have a tendency to appear in clusters instead of scattered along the time frame. Identifying clusters and estimating their…
Chaos near a reversible homoclinic bifocus
Pablo G. Barrientos, Artem Raibekas, Alexandre A. P. Rodrigues
We show that any neighborhood of a non-degenerate reversible bifocal homoclinic orbit contains chaotic suspended invariant sets on -symbols for all . This will be achie…
Failure Rate Properties of Parallel Systems
Idir Arab, Milto Hadjikyriakou, Paulo Eduardo Oliveira
We study failure rate monotonicity and generalized convex transform stochastic ordering properties of random variables, with a concern on applications. We are especially interested…
Dynamic interpolation for obstacle avoidance on Riemannian manifolds
Anthony Bloch, Margarida Camarinha, Leonardo Colombo
This work is devoted to studying dynamic interpolation for obstacle avoidance. This is a problem that consists of minimizing a suitable energy functional among a set of admissible…
Kazantsev dynamo in turbulent compressible flows
Marco Martins Afonso, Dhrubaditya Mitra, Dario Vincenzi
We consider the kinematic fluctuation dynamo problem in a flow that is random, white-in-time, with both solenoidal and potential components. This model is a generalization of the w…
Non self-adjoint operators with real spectra and extensions of quantum mechanics
N. Bebiano, J. da Providência
In this article, we review the general quantum mechanical setting associated to a non self-adjoint Hamiltonian with real spectrum. Spectral properties of the Hamiltonian of a simpl…
Equilibrium states for a class of skew-products
Maria Carvalho, Sebastián A. Pérez
We consider skew-products on , where is the two-sphere or the two-torus, which are partially hyperbolic and semi-conjugate to an Axiom A diffeomorphism. T…
Dynamical counterexamples regarding the Extremal Index and the mean of the limiting cluster size distribution
Miguel Abadi, Ana Cristina Moreira Freitas, Jorge Milhazes Freitas
The Extremal Index is a parameter that measures the intensity of clustering of rare events and is usually equal to the reciprocal of the mean of the limiting cluster size distribut…
Generating maximal subgroups of finite almost simple groups
Andrea Lucchini, Claude Marion, Gareth Tracey
For a finite group , let denote the minimal number of elements required to generate . In this paper, given a finite almost simple group and any maximal subgroup $H…
Continuity of the core-EP inverse and its applications
Yuefeng Gao, Jianlong Chen, Pedro Patricio
In this paper, firstly we study the continuity of the core-EP inverse without explicit error bounds by virtue of two methods. One is the rank equality, followed from the classical…
Hénon-like families and blender-horseshoes at non-transverse heterodimensional cycles
Lorenzo J. Díaz, Sebastián A. Pérez
In dimension three and under certain regularity assumptions, we construct a renormalisation scheme at the heterodimensional tangency of a non-transverse heterodimensional cycle ass…
The eigenstructures of real (skew) circulant matrices with some applications
Zhongyun Liu, Siheng Chen, Weijin Xu +1
The circulant matrices and skew-circulant matrices are two special classes of Toeplitz matrices and play vital roles in the computation of Toeplitz matrices. In this paper, we focu…
The universal Lie -algebroid of a singular foliation
Camille Laurent-Gengoux, Sylvain Lavau, Thomas Strobl
We associate a Lie -algebroid to every resolution of a singular foliation, where we consider a singular foliation as a locally generated -submodule of vector f…
Lévy processes with respect to the index Whittaker convolution
Rúben Sousa, Manuel Guerra, Semyon Yakubovich
The index Whittaker convolution operator, recently introduced by the authors, gives rise to a convolution measure algebra having the property that the convolution of probability me…
Homotopy Type of Moduli Spaces of G-Higgs Bundles and Reducibility of the Nilpotent Cone
C. Florentino, P. B. Gothen, A. Nozad
Let be a real reductive Lie group, and the complexification of its maximal compact subgroup . We consider classes of semistable -Higgs bundles o…
Simplicity of augmentation submodules for transformation monoids
M. H. Shahzamanian, B. Steinberg
For finite permutation groups, simplicity of the augmentation submodule is equivalent to -transitivity over the field of complex numbers. We note that this is not the case for t…