Noticias en español
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.
Coarse Graph Theory I – The Questions
Resumen: Coarse graph theory is concerned with the large-scale geometric properties of infinite graphs, especially the properties preserved by quasi-isometries. Although such inquiries have been raised since the 80’s, it was usually in the context of Cayley graphs and geometric group theory. Recently the topic migrated to graph theory with intriguing outcomes. Eventually, the field of coarse graph theory was officially inaugurated and systematically treated in a paper by Georgakopoulos and Papasoglu. In this talk, I will explain...
Aggregating opinions — do we need (Kolmogorov) complexity?
Abstract: Imagine a group of people that need each day to make some collective decision (for the entire group), choosing one of two options A and B. Some people prefer A, some prefer B, and others are OK with any of the two options. (The next day the preferences may change arbitrarily, and a new group choice is made.) The group management needs to choose A or B, in both cases making some people unhappy. This cannot be avoided completely (if someone wants A and someone else wants B, one of them will be unhappy), so the goal is more modest:...
A spectral proof of Szemerédi’s regularity lemma.
Resumen: In this talk I will present the spectral proof of the regularity lemma due to Frieze and Kannan in the version popularized by Tao.
Algebraic intersections in translation surface.
RESUMEN: The purpose of this talk is to discuss the maximal possible (algebraic) intersection of closed curves of a given length on translation surfaces. One way to quantify this is to define the so-called “interaction strength” of the surface. The (moduli) space of translation surfaces comes with a natural SL(2,ℝ)-action and we are interested in understanding the behaviour of the interaction stength under this action. After having introduced translation surfaces and the SL(2,ℝ)-action, we will give a few geometric ideas and focus...
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...
On 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,...
Copositive 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.
Modeling 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.
