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.
Quantum dissipative systems.
Abstract: The problem of modeling dissipative effects in quantum physics dates back to the 1970s. After reviewing the main challenges associated with developing such models, I will present a specific model introduced by Bruneau and De Bièvre in the early 2000s. This model describes the interactions between a classical particle and an abstract environment, where the environment acts on the classical particle as a linear friction force. One of the key strengths of this approach is that it can be naturally extended to the quantum setting. In the...
The inverse elasticity problem, its extension to porous media and applications in biomedicine.
RESUMEN: The inverse elasticity problem can be simply stated as: given a deformed configuration and the forces that act on it, find an initial stress-free configuration such that when the given forces are applied to it, one recovers the given deformed configuration. Surprisingly, this problem can be framed as a (direct) elasticity one, whose mathematical properties are inherited from the original direct problem if the underlying material is sufficiently regular. In this seminar, I will review this problem and its main mathematical properties....
Speciation induced by dormancy in a model with changing environment.
Resumen: We consider a population model in which the season alternates between winter and summer. Individuals can acquire mutations that are advantageous in the summer but disadvantageous in the winter, or vice versa. Furthermore, it is assumed that individuals within the population can either be active or dormant, and that individuals can transition between these two states. Dormant individuals do not reproduce and are not subject to selective pressures. Our findings indicate that, under some conditions, two waves of adaptation emerge...
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...
Randomized block-coordinate descent beyond gradient global Lipschitz continuity
Abstract: Randomized block-coordinate algorithms are recognized to furnish efficient iterative schemes for addressing large-scale problems, especially when the computation of full derivatives entails substantial memory requirements and computational efforts. Classically, the convergence analysis of these methods relies on a standard assumption of global Lipschitz continuity of partial gradients of differentiable functions. This compromises its applicability to situations where gradient Lipschitz continuity is violated, for instance, in...
Robust Admission via Two-Stage Stable Matching under Ranking Uncertainty.
Abstract: The Bachillerato Inicia UC program offers a pathway for students from Chilean technical high schools to articulate into undergraduate programs at Pontificia Universidad Católica de Chile. Upon applying, candidates rank up to three preferred programs. However, articulation is determined only after one year, based on their academic ranking within the cohort – a value unknown at the time of admission. This setting gives rise to a two-stage admission problem with downstream matching constraints and exogenous uncertainty. The...
Fracture of heterogeneous materials: a phase-field approach.
ABSTRACT: In this talk, I will describe recent attempts at devising a rigorous framework for the analysis and numerical simulation of crack propagation in heterogeneous materials. I will focus on the challenge of devising a mathematically sound and mechanistically coherent concept of effective toughness and computing it. I will first explain how classical theories such as homogenization fail to provide a meaningful answer to this question. Then, I will propose a framework based on the idea of computational homogenization in trajectory space....
Balancedness Constants of Words Generated By Billiards in The Hypercube.
RESUMEN In this talk, I will consider words generated by coding the trajectory of a ball inside a hypercubic billiard table. Balancedness is a combinatorial notion related to the dynamical concept of discrepancy, which characterizes square billiard words. It is then natural to ask: what is the imbalance (i.e., the optimal balancedness constant) of hypercubic billiard words in higher dimensions? After reviewing the partial results obtained by Vuillon in 2003, I will present a complete characterization of the imbalances of hypercubic...
Datos de observación de la Tierra para evaluar el impacto del cambio climático en los cambios de uso de suelo en Chile
En el seminario se abordará cómo las sequías prolongadas, intensificadas por el cambio climático, están transformando la cobertura terrestre en Chile. La investigación presentada analiza el impacto de los cambios acumulativos en la oferta y demanda de agua —en distintas escalas temporales— sobre la productividad vegetal y el uso de suelo, en el contexto de la megasequía que afecta al país desde 2010.
Analyzing the (k-)swap neighborhood for makespan scheduling.
Abstract: Analyzing the behavior of local search methods has received considerable attention over the last two decades. One interesting question is how the simplest form of local search, i.e., iterative improvement, behaves w.r.t. a certain neighborhood both in quality of the solution as well as number of iterations needed to obtain a local optimal solution. In this talk, we consider the basic scheduling problem in which n jobs need to be scheduled on m identical machines so as to minimize the makespan, i.e., the completion time of the last...
