Seminars

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.

 

Asymptotic analysis of a  population dynamics with competition and horizontal transfer.

Event Date: Dec 09, 2020 in Seminario Probabilidades CMM, Seminars

Resumen:  We present a model for the dynamics of a population of bacteria with trait structure, who compete for resources and exchange genetic material by horizontal transfer. Phenotypic traits characterizing individuals may then be vertically inherited through mutations, and horizontally transmitted through transfer. Competition and horizontal transfer influence individual demographics and population size, which in turn feeds back on the dynamics of competitions and transfers. We consider a stochastic individual-based pure jump process...

Counting integer partitions with the method of maximum entropy.

Event Date: Dec 09, 2020 in ACGO, Seminars

  Abstract: The problem of asymptotically counting integer partitions has a long and storied history, beginning with the pioneering work of Hardy and Ramanujan in 1918. In the work presented here, we give a probabilistic perspective on this problem, and use this approach to prove an asymptotic formula for the number of partitions of an integer n where the sums of the kth powers of the parts are also fixed, for some collection of values k. To obtain this result, we reframe the counting problem as an optimization problem, and find the...

Ciclos hamiltonianos y simetría en los niveles medios del hipercubo.

Event Date: Dec 03, 2020 in Seminario de Grafos, Seminars

Abstract: Consideremos el grafo de los niveles medios que tiene como vértices todos los bitstrings de largo 2n+1 con exactamente n o n+1 unos, y aristas entre todo par de bitstrings que difieren en exactamente una coordenada. El recientemente demostrado teorema de los niveles medios dicta que este grafo tiene un ciclo hamiltoniano. Siendo los niveles medios un grafo altamente simétrico, este teorema es uno de los ejemplos más notables de la conjetura de Lovász: Todo grafo conexo y altamente simétrico (salvo 5 excepciones) tiene un ciclo...

Linear response formula for the topological entropy at the time one map of a geodesic flow on a manifold of negative curvature.

Event Date: Dec 02, 2020 in Dynamical Systems, Seminars

ABSTRACT Let be the time one map of a geodesic flow on a manifold of constant negative curvature with its Liouville measure. Consider , a family of diffeomorphisms with . In this talk we discuss about the differentiability of the map at , and we provide an explicit formula for its derivative.

Matroids, polymatroids and submodular functions: algebra or optimization?

Event Date: Dec 02, 2020 in ACGO, Seminars

Abstract: Matroids, polymatroids and submodular functions are beautiful objects that have appeared in many areas of mathematics including algebra, geometry, topology and optimization. Consequently, they have been studied from multiple points of view. This oftentimes has the consequence that the same results are proven from different points of view and by very different communities. A notable example being their study in optimization and algebraic combinatorics. The goal of this talk is to tell this story, show how a small mixture of ideas...

Elapsed time neural assemblies and learning processes for weak interconnections.

Event Date: Dec 01, 2020 in Differential Equations, Seminars

Abstract: Modeling neural networks is an interesting problem from both mathematical and neuroscience point of view. In particular, evolution equations describing neural assemblies derived from stochastic processes and microscopic models have become a very active area in recent years. In this context we study a neural network via time-elapsed dynamics with learning, where neurons are described by their position in brain cortex and the elapsed time since last discharge. The learning process is modeled via the change in the interconnections...

Notas sobre expansividad positiva para semiflujos continuos.

Event Date: Nov 25, 2020 in Dynamical Systems, Seminars

ABSTRACT: En esta charla probaremos que si X es un espacio métrico y $\phi$ es un semiflujo continuo positivamente expansivo, en el sentido de Alves, Carvalho y Siqueira (2017), entonces el semiflujo $\phi$ es trivial y el espacio X es uniformemente discreto. En particular, si X es compacto, entonces es un conjunto finito.

An optimal algorithm for strict circular seriation.

Event Date: Nov 25, 2020 in ACGO, Seminars

Abstract: Seriation is an exploratory combinatorial data analysis technique to reorder objects into a sequence along a one-dimensional continuum when the only available information among the objects is their pairwise similarity (or dissimilarity). Linear seriation aims at inferring an ordering (permutation) consistent with an underlying linear order of the data. In many cases however, the data objects may be arranged around a closed continuum yielding a rather circular underlying order. In a matrix representation, this can be visualized as a...

Conjetura de Ryser en hipergrafos t-intersectantes.

Event Date: Nov 19, 2020 in Seminario de Grafos, Seminars

Resumen: La conjetura de Ryser establece que el número de cover de un hipergrafo r-partito r-uniforme es a lo más (r-1)  veces el tamaño de su número de matching. En esta charla, revisaremos avances recientes en cotas para la conjetura en hipergrafos t intersectantes dadas ciertas restricciones asociadas a r y t.