Futuros Eventos

Seminario de Sistemas Dinámicos
Marcelo Sobottka. Ufsc
Curtis-Hedlund-Lyndon Theorem for Ultragraph Shift Spaces
Sala von Neumann, CMM
In this work we characterize the class of continuous shift commuting maps between ultragraph shift spaces, proving a Curtis-Hedlund-Lyndon type theorem. Then we use it to characterize continuous, shift commuting, length preserving maps in terms of generalized sliding block codes.

This is a joint work with Prof. Daniel Gonçalves  (UFSC, Brazil) 

Eventos Pasados

Seminario de Sistemas Dinámicos
Piere Berger. Paris Xiii
The Herman positive entropy conjecture
We show that any sympletic $C^\infty$-diffeomorphism which displays a non-hyperbolic periodic point can be $C^\infty$-approximated by a symplectic one whose metric entropy is positive.

The proof involves developments of the concept of universal dynamics, some developments of Katok, Przytycki, Arroyo-Pujals examples, and new techniques to ensure that up to the composition with a map of the form
$(x,y)\mapsto (x,y+\phi(x))$ with $\phi$ small, some heteroclinic links can be restored (i.e. the stable and unstable manifolds of some hyperbolic periodic points coincide).

Joint work with Dimitry Turaev.
Sala 1, PUC
Seminario de Probabilidad
Luis Fredes. Bordeaux
Invariant mesures of discrete interacting particle systems: algebraic aspects
We consider a continuous time particle system on a graph L being either Z,  Z_n, a segment {1,…, n}, or Z^d, with state space Ek={0,…,k-1} for some k belonging to {infinity, 2, 3, …}. We also assume that the Markovian evolution is driven by some translation invariant local dynamics with bounded width dependence, encoded by a rate matrix T. These are standard settings, satisfied by many studied particle systems. We provide some sufficient and/or necessary conditions on the matrix T, so that this Markov process admits some simple invariant distribution, as a product measure, as the distribution of a Markov process indexed by Z or {1,…, n} (if L=Z or {1,…,n}), or as a Gibbs measure (if L=Z_n). These results are mainly obtained with some manipulations of finite words, with alphabet Ek, representing subconfigurations of the systems. For the case L=Z, we give a procedure to find the set of invariant i.i.d and Markov measures.
Sala John Von Neumann, 7mo piso, CMM
12:00 hrs.
Seminario Agco
Kurt Melhorn. Instituto Max-Planck de Informática
Markets and Fair Division of Goods
República 779 B, Sala 3er Piso.
14:30 hrs.
Seminario Agco
Alfredo Torrico. Gatech
Robust Submodular Maximization: Offline and Online algorithms
República 779 B, Sala 3er Piso.