Seminars appear in decreasing order in relation to date. To find an activity of your interest just go down on the list. Normally seminars are given in english. If not, they will be marked as **Spanish Only.**

## On the action of the semigroup of non singular integral matrices on $\R^n$

Abstract. Let Γ be the multiplicative semigroup of all n × n matrices with integral entries and nonzero determinant. Let 1 ≤ p ≤ n−1 and V = Rnp = Rn ⊕···⊕Rn (p copies). Consider the action of Γ on V , given by the natural action on each component, by matrix multiplication on the left. Then for x= (x1, . . . , xp) ∈ V , the Γ-orbit is dense in V if and only if there is no linear combination pj=1 λjxj, with λj ̸= 0 for some j, which is a rational vector in Rn; in fact the assertion holds also for the orbit of the subgroup SL(n, Z) that...

## Decidability of the isomorphism and the factorization for minimal substitution subshifts

ABSTRACT Classification is a central problem in the study of dynamical systems, in particular for families of systems that arise in a wide range of topics. Hence it is important to have algorithms deciding wether a dynamical system have some given property. Let us mention subshifts of finite type that appear, for example, in information theory, hyperbolic dynamics, $C^*$-algebra, statistical mechanics and thermodynamic formalism. The most important and longstanding open problem for this family originates in [Williams:1973] and is stated in...

## Resonances in deformed tubes: twisting and bending & Gross-Pitaevskii equation and integrable systems

16:00 hrs. Expositor Pablo Miranda, (USach) Título Resonances in deformed tubes: twisting and bending Abstract: In this talk we will consider an infinite straight tube and we will deform it by a periodic twisting and a local bending. On the deformed tube we will define the Laplacian and will study the existence of scattering resonances created by the deformations. We will show the existence of exactly one resonance or one eigenvalue near the bottom of the essential spectrum, depending on the strength of the twisting and the bending. We...

## An approach to optimality in convex optimization via some new Moreau- Rockafellar type formulas for the subdifferential of the supremum function.

Abstract: We present different characterizations of the subdifferential of the supremum function of finitely and infinitely indexed families of convex functions under weak continuity assumptions. The resulting formulas are given in terms of the exact subdifferential of the data functions at the reference point, and not at nearby points. Based on these characterizations we give new Fritz-John and KKT-type optimality conditions for semi-infinite convex optimization, dropping out the typical continuity/closedness assumptions which are usual in...

## Confort y la calidad climática en el Espacio Público. Estudio de caso: ciudad de Chillán, Chile

Seminarios de la Alianza Copernicus-Chile Titulo Confort y la calidad climática en el Espacio Público. Estudio de caso: ciudad de Chillán, Chile Expositor Pamela Smith U. de Chile Sala: Sala Multimedia, Centro de Modelamiento Matemático, Beauchef 851, Edificio Norte, Piso 6. Fecha: Lunes 05 de Noviembre de 2018 Hora: 16:00 horas Participación en Linea: http://vcespresso.redclara.net/@352109705c115cdd511fb968f9f4ff86# Use Explorer, Firefox o Safari, debe tener instalado Flash Player...

## Almost everywhere convergence of ergodic averages

ABSTRACT: In this talk I would like to discuss some of my results concerning almost everywhere convergence of non-conventional ergodic averages of L1 functions. These topics include: divergence of ergodic averages along the squares; convergence along some sequences of zero Banach density; convergence for arithmetic weights: the prime divisor functions ω and Ω.

## Particles-based simulations and GPU computing for soft matter science and computer graphics applications

Summary: Particle-based simulation codes used in soft matter science aim at represent the interactions that occur in colloidal suspensions at nanoscale level. These suspensions are a mixture of solid particles of diameter between 100 and 1000 nanometers and a solvent (usually water), all interacting with each other. The main goal when implementing these codes on the GPU is to accelerate the “particle neighbour searching” phase, which is the bottleneck in most lagrangian-based simulations. I will present recent results...

## “Second-order characterizations of C1-smooth robustly quasiconvex functions”

Abstract: “Our aim in this talk is to investigate the possibility of using the Fréchet and Mordukhovich second-order subdifferentials to characterize the robust quasiconvexity of C1-smooth functions. We set up a necessary condition for the robust quasiconvexity of C1,1-smooth functions and univariate C1-smooth ones. We also show that the established necessary condition is indeed a sufficient one for the robust quasiconvexity of C1-smooth functions.”

## El Cubo de Datos de Colombia

Seminarios de la Alianza Copernicus-Chile Titulo El Cubo de Datos de Colombia Expositor Pilar Lozano, IDEAM Sala: Sala Multimedia, Centro de Modelamiento Matemático, Beauchef 851, Edificio Norte, Piso 6. Fecha: Lunes 22 de Octubre de 2018 Hora: 16:00 horas Participación en Linea: http://vcespresso.redclara.net/@352109705c115cdd511fb968f9f4ff86# Use Explorer, Firefox o Safari, debe tener instalado Flash Player...