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.
Deterministic Impartial Selection with Weights.
Abstract: In the impartial selection problem, a subset of agents up to a fixed size k among a group of n is to be chosen based on votes cast by the agents themselves. A selection mechanism is impartial if no agent can influence its own chance of being selected by changing its vote. It is \alpha-optimal if, for every instance, the ratio between the votes received by the selected subset is at least a fraction of \alpha of the votes received by the subset of size k with the highest number of votes. We study deterministic impartial mechanisms in...
Inverse and reverse optimization problems.
Abstract: nverse and reverse optimization problems aim to adjust the objective function of an underlying optimization problem while minimizing the extent of modification. In inverse optimization, the goal is to modify the objective function so that a given feasible solution becomes optimal. In reverse optimization, the goal is to modify the objective function so that the optimum value attains a specified number. In this talk, we mainly focus on inverse maximum-capacity optimization problems under the bottleneck Hamming distance, the weighted...
The Korteweg-de Vries on the general star graphs
Abstract: In this talk, we discuss local well-posedness for the Cauchy problem associated with the Korteweg-de Vries (KdV) equation on a general metric star graph. The graph comprises (m+k) semi-infinite edges: k negative half-lines and m positive half-lines, all joined at a common vertex. The choice of boundary conditions is compatible with the conditions determined by the semigroup theory. The crucial point in this work is to obtain the integral formula using the forcing operator method. This work extends the previous results obtained by...
Well-Posedness results for non-isotropic perturbations of the nonlinear Schrödinger equation on cylindrical domains
Abstract: We consider a non-isotropically perturbed nonlinear Schrödinger equation posed on two-dimensional cylindrical domains of the form T×R T and R×T. This equation arises in models describing wave propagation in fiber arrays. In this talk, we present several well-posedness results for initial data belonging to Sobolev spaces. For the cylindrical domain T×R, we establish global well-posedness in L^2xL^2 for small initial data by proving an L^4 – L^2 Strichartz-type inequality. In the case of the domain R×T, we were unable to adapt...
Maker-Breaker games on Galton-Watson tres.
Resumen: Maker-Breaker is a classical combinatorial game in which one player fixates, the other one removes edges (taking turns) in order to connect/isolate nodes. This two-player game is considered on the random board given by the family tree of a supercritical Galton-Watson branching proces Strategies and success probabilities are assessed for different levels of information, the players receive during play.
Deterministic and stochastic fixed-point iterations in normed spaces.
Abstract: In this talk, we present a survey of techniques and results on error bounds and convergence rates for both deterministic and stochastic fixed-point iterations, with a focus on methods such as the Krasnoselskii-Mann and Halpern iterations. Our primary emphasis is on general normed spaces, where we employ tools from optimal transport to derive tight error bounds. For spaces with additional structure, such as Hilbert spaces, we also discuss existing techniques and the sharp results established in the literature. Finally, we highlight...
On the complexity of the CSP.
Abstract: The Constraint Satisfaction Problem (CSP) is defined as follows: we are given a set of variables, a set of values, and a set of constraints, where each constraint restricts the combination of values that certain tuple of variables can take. The question is whether there exists an assignment of values to the variables that satisfies all the constraints. The CSP is a well-known NP-complete problem, and hence much research has been done to identify restrictions of this problem that can be solved in polynomial time. In this talk, we...
What to align in multimodal contrastive learning?
Abstract: Humans perceive the world through multisensory integration, blending the information of different modalities to adapt their behavior. Contrastive learning offers an appealing solution for multimodal self-supervised learning. Indeed, by considering each modality as a different view of the same entity, it learns to align features of different modalities in a shared representation space. However, this approach is intrinsically limited as it only learns shared or redundant information between modalities, while multimodal interactions...
Some dynamical invariants under strong orbit equivalence.
Abstract: A dynamical system is usually made up of a state space and a rule (a map acting on the space) that tells us how the system evolves over time. One of the central questions in studying these systems is figuring out when two of them are essentially the same, or conjugate, as we usually say. There are several known features, called invariants, that stay the same under conjugacy, but so far, no single invariant can completely characterize when two systems are conjugate. Because of that, it is natural to look at a slightly weaker idea of...
