Noticias en español
Tariff Zone Assignment: Complexity Results ans Solution Approaches.
Abstract: In the Tariff Zone Assignment problem, an operator is tasked with partitioning a transport network (i.e., a graph) into tariff zones in order to maximize revenue under a linear pricing model. In this model, customers pay a price proportional to the number of zones traveled through, up to some maximum accepted price. If this price gets exceeded, customers drop out of the model and thus generate no revenue at all. In this talk, first we will look at the complexity of this problem and show APX-hardness on star graphs and strong NP-hardness on paths. These complexity results motivate...
Read MoreOn Bernoulli Trials with unequal harmonic success probability.
Resumen: A Bernoulli scheme with unequal harmonic success probabilities is investigated, together with some if its natural extensions. The study includes the number of successes over some time window, the times to (between) successive successes and the time to the first success. Large sample asymptotics, parameter estimation, and relations to Sibuya distributions and Yule–Simon distributions are briefly discussed. Stirling numbers play a key role in the analysis. This toy model is relevant in several applications including reliability, species sampling problems, record values breaking and...
Read MoreFamilias test para comprobar la promediabilidad de grupos residualmente finitos.
RESUMEN: Un clásico resultado establece que un grupo numerable G es promediable (amenable), si y sólo si toda acción continua de G sobre un espacio métrico compacto admite medidas de probabilidad invariantes. Motivados por esta caracterización de promediabilidad, Giordano y de la Harpe mostraron que para testear promediabilidad de un grupo G, basta con estudiar las acciones continuas de G sobre el Cantor. En otras palabras, probaron que las acciones continuas sobre el Cantor son una familia test para la promediabilidad de un grupo numerable. Una aplicación directa del resultado de Giordano...
Read MoreModeling Population Dynamics with PDEs? SIPodemos!
Summary: In this talk, I will present some facets of the best known equation in reaction-diffusion, which is called the Fisher KPP equation. I will explain where it comes from and what kind of results are interesting for mathematicians. Nobody needs knowledge in PDEs, the only thing to know is what is a Laplacian in R^d, or partial derivatives of order 2.
Read MoreCopositive and Linear Conic Optimization Revisited via Linear Semi-Infinite Optimization.
Abstract: In this talk we show existence, optimization and duality theorems for copositive and linear conic optimization problems. These results are obtained from the semi-infinite linear optimization theory, which has been previously updated in two articles in collaboration with Andrea Ridolfi and Virginia Vera de Serio.
Read MoreSharp large deviation principles for descents of random permutations.
Resumen: A permutation $\pi_n$ of size $n$ is said to have a descent at position $k$ if $\pi_n(k) > \pi_n(k + 1)$. We define $D_n$ as the number of descents of $\pi_n$, and $D_n’$ as the number of descents of $\pi_n^{-1}$, the inverse permutation of $\pi_n$. In this talk, I will present recent developments regarding the sharp large deviations for $D_n$ and for the pair $(D_n, D_n’)$, along with other probabilistic results when $\pi_n$ is taken uniformly at random from $S_n$, the set of permutations of size $n$. Work in collaboration with B. Bercu, M. Bonnefont, and A....
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