Seminars

Improving Sea Surface Temperature Products with Deep Learning in the Copernicus Marine Service

Event Date: Sep 05, 2025 in Ciclo de Seminarios quincenales de la Alianza Copernicus-Chile, Seminars

Event Date: Aug 26, 2025 in Seminario de Grafos, Seminars

Abstract: For a family of graphs H, a graph G is H-free if no induced subgraph of G is isomorphic to a graph in H. In this talk, I will present a new decomposition theorem and coloring algorithm for(2P_3,C_4,C_6)-free graphs. I will also give some background on Truemper configurations (thetas, pyramids, prisms, and wheels) and on proving decomposition theorems in general

Canonical Ramsey numbers for partite hypergraphs.

Event Date: Sep 02, 2025 in Seminario de Grafos, Seminars

Abstract: Ramsey’s theorem states that for sufficiently large n, any r-colouring of the edges of the complete k-uniform hypergraph on n vertices contains a monochromatic copy of the complete k-uniform hypergraph on t vertices. Erdős and Rado generalised this result to an unbounded number of colours. They characterised all canonical colour patterns that are unavoidable in edge colourings of sufficiently large complete hypergraphs. We consider quantitative aspects of this result. For Erdős and Rado’s theorem, both the lower and upper bound on n grow as (k-1)-times iterated...

Two-Edge Connectivity via Pac-Man Gluing.

Event Date: Sep 02, 2025 in Seminars, SIPo (Seminario de Investigadores Postdoctorales)

Abstract: We study the 2-edge-connected spanning subgraph (2-ECSS) problem: Given a graph $G$, compute a connected subgraph $H$ of $G$ with the minimum number of edges such that $H$ is spanning, i.e., $V(H) = V(G)$, and $H$ is 2-edge-connected, i.e., $H$ remains connected upon the deletion of any single edge, if such an $H$ exists. The $2$-ECSS problem is known to be NP-hard. In this work, we provide a polynomial-time $(\frac 5 4 + \varepsilon)$-approximation for the problem for an arbitrarily small $\varepsilon>0$, improving the previous best approximation ratio of...

Stochastic processes, transport of mass, and functional inequalities.

Event Date: Aug 27, 2025 in Seminario de Probabilidades de Chile, Seminars

Resumen:   Functional inequalities have proven to be a ubiquitous tool in mathematics, especially in probability theory. For example, they are closely related to the concentration of measure phenomenon, and they help quantify the rate at which ergodic Markov processes converge to equilibrium. Prominent examples of those inequalities include the families of logarithmic Sobolev, Poincaré, and transport-entropy inequalities. In the first part of the talk, I will provide an introduction to this topic, highlighting the classical examples, results, and applications. In the second part of the talk,...

Sistemas substitutivos y S-ádicos más allá de los grupos abelianos

Event Date: Aug 25, 2025 in Dynamical Systems, Seminars

RESUMEN: Los sistemas sustitutivos y S-ádicos tienen una rica teoría en el marco unidimensional y multidimensional, lo que proporciona herramientas poderosas para el estudio de los subshifts. Con el objetivo de recuperar estas herramientas para las acciones de grupo, en esta presentación mostraré cómo podemos extender el concepto de sustituciones a los grupos numerables. Exploraré cómo diferentes clases de grupos admiten diferentes tipos de descomposiciones jerárquicas que permiten definir subshifts sustitutivos y S-ádicos. Luego mostraré cómo recuperar los resultados clásicos sobre...