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
29 papers · 1 filter
Topological Complexity of the Klein bottle
Daniel C. Cohen, Lucile Vandembroucq
We show that the (normalized) topological complexity of the Klein bottle is . We also show that, for any , . This completes the recent work by Dranishnikov o…
On some categorical-algebraic conditions in S-protomodular categories
Nelson Martins-Ferreira, Andrea Montoli, Manuela Sobral
In the context of protomodular categories, several additional conditions have been considered in order to obtain a closer group-like behavior. Among them are locally algebraic cart…
A note on the finite basis and finite rank properties for pseudovarieties of semigroups
J. Almeida, M. H. Shahzamanian
The finite basis property is often connected with the finite rank property, which it entails. Many examples have been produced of finite rank varieties which are not finitely based…
On the conservative pasting lemma
Pedro Teixeira
Several perturbation tools are established in the volume preserving setting allowing for the pasting, extension, localized smoothing and local linearization of vector fields. The p…
Barrier Option Pricing under the 2-Hypergeometric Stochastic Volatility Model
Rúben Sousa, Ana Bela Cruzeiro, Manuel Guerra
We investigate the pricing of financial options under the 2-hypergeometric stochastic volatility model. This is an analytically tractable model that reproduces the volatility smile…
Characterizations and representations of core and dual core inverses
Jianlong Chen, Huihui Zhu, Pedro Patricio +1
In this paper, double commutativity and the reverse order law for the core inverse are considered. Then, new characterizations of the Moore-Penrose inverse of a regular element are…
Stability of a leap-frog discontinuous Galerkin method for time-domain Maxwell's equations in anisotropic materials
Adérito Araújo, Sílvia Barbeiro, Maryam Khaksar Ghalati
In this work we discuss the numerical discretization of the time-dependent Maxwell's equations using a fully explicit leap-frog type discontinuous Galerkin method. We present a suf…
Combined role of molecular diffusion, mean streaming and helicity in the eddy diffusivity of short-correlated random flows
Marco Martins Afonso, Andrea Mazzino, Sílvio Gama
We analytically investigate the effective-diffusivity tensor of a tracer particle in a fluid flow endowed with a short correlation time. By means of functional calculus and a multi…
Reducibility versus definability for pseudovarieties of semigroups
J. Almeida, O. Klíma
It is easy to show that a pseudovariety which is reducible with respect to an implicit signature for the equation can also be defined by -identities. We present severa…
Centralizer's applications to the inverse along an element
Huihui Zhu, Jianlong Chen, Pedro Patricio +1
In this paper, we first prove that the absorption law for one-sided inverses along an element holds, deriving the absorption law for the inverse along an element. We then apply thi…
Extreme Value Laws for dynamical systems with countable extremal sets
Davide Azevedo, Ana Cristina Moreira Freitas, Jorge Milhazes Freitas +1
We consider stationary stochastic processes arising from dynamical systems by evaluating a given observable along the orbits of the system. We focus on the extremal behaviour of th…
New conserved currents for vacuum space-times in dimension four with a Killing vector
Alfonso García-Parrado Gómez-Lobo
A new family of conserved currents for vacuum space-times with a Killing vector is presented. The currents are constructed from the superenergy tensor of the Mars-Simon tensor and…
Two characterisations of groups amongst monoids
Andrea Montoli, Diana Rodelo, Tim Van der Linden
The aim of this paper is to solve a problem proposed by Dominique Bourn: to provide a categorical-algebraic characterisation of groups amongst monoids and of rings amongst semiring…
On Takens' Last Problem: tangencies and time averages near heteroclinic networks
Isabel S. Labouriau, Alexandre A. P. Rodrigues
We obtain a structurally stable family of smooth ordinary differential equations exhibiting heteroclinic tangencies for a dense subset of parameters. We use this to find vector fie…
Extremes and Recurrence in Dynamical Systems
Valerio Lucarini, Davide Faranda, Ana Cristina Moreira Freitas +6
This book provides a comprehensive introduction for the study of extreme events in the context of dynamical systems. The introduction provides a broad overview of the interdiscipli…
Global Saddles for Planar Maps
Begoña Alarcón, Sofia B. S. D. Castro, Isabel S. Labouriau
We study the dynamics of planar diffeomorphisms having a unique fixed point that is a hyperbolic local saddle. We obtain sufficient conditions under which the fixed point is a glob…
Relative information entropy in cosmology: The problem of information entanglement
Viktor G. Czinner, Filipe C. Mena
The necessary information to distinguish a local inhomogeneous mass density field from its spatial average on a compact domain of the universe can be measured by relative informati…
On statistical properties for equilibrium states of partially hyperbolic horseshoes
Vanessa Ramos, Jaqueline Siqueira
We derive some statistical properties for equilibrium states of partially hyperbolic horseshoes. We define a projection map associated to the horseshoe and prove a spectral gap for…
The semaphore codes attached to a Turing machine via resets and their various limits
John Rhodes, Anne Schilling, Pedro V. Silva
We introduce semaphore codes associated to a Turing machine via resets. Semaphore codes provide an approximation theory for resets. In this paper we generalize the set-up of our pr…
On time adaptive critical variable exponent vectorial diffusion flows and their applications in image processing
V. B. Surya Prasath, D. Vorotnikov
Variable exponent spaces have found interesting applications in real world problems. Recently, there have been considerable interest in utilizing variational and evolution problems…
What is an ideal a zero-class of?
N. Martins-Ferreira, A. Montoli, A. Ursini +1
We characterise, in pointed regular categories, the ideals as the zero-classes of surjective relations. Moreover, we study a variation of the "Smith is Huq" condition: two surjecti…
Vacuum type D initial data
Alfonso García-Parrado Gómez-Lobo
A vacuum type D initial data set is a vacuum initial data set of the Einstein field equations whose data development contains a region where the space-time is of Petrov type D. In…
A Coinductive Approach to Proof Search through Typed Lambda-Calculi
José Espírito Santo, Ralph Matthes, Luís Pinto
In reductive proof search, proofs are naturally generalized by solutions, comprising all possibly infinite structures generated by locally correct, bottom-up application of inferen…
Birationality of moduli spaces of twisted -Higgs bundles
Peter B. Gothen, Azizeh Nozad
A -Higgs bundle on a Riemann surface (twisted by a line bundle) consists of a pair of holomorphic vector bundles, together with a pair of (twisted) maps between th…