Nom de l'orateur
Simone Vantini
Etablissement de l'orateur
Politecnico Milano
Lieu de l'exposé
Salle des séminaires
Date et heure de l'exposé

The talk will deal with the key challenge of creating prediction sets in the functional data framework. Starting from the investigation of the literature concerning this topic, we propose an innovative approach building on top of Conformal Prediction able to overcome the main drawbacks characterizing the existing approaches. We will show how the new proposed nonparametric method is able to construct finite-sample either valid or exact prediction bands under minimal distributional assumptions.

Nom de l'orateur
Yuichi Ike
Etablissement de l'orateur
University of Tokyo
Lieu de l'exposé
Salle Éole
Date et heure de l'exposé

The interleaving distance is a canonical pseudo-distance for persistence modules and plays an essential role in topological data analysis. After the pioneering work by Curry, Kashiwara and Schapira introduced the interleaving distance on the category of sheaves and studied its stability property. In this talk, I will explain that we can use this distance for sheaves to get a lower bound of the Hamiltonian displacement energy in a cotangent bundle through its stability with respect to Hamiltonian deformations.

Nom de l'orateur
Cristóbal Meroño
Etablissement de l'orateur
Universidad Politécnica de Madrid
Lieu de l'exposé
salle des séminaires
Date et heure de l'exposé

Uniqueness and reconstruction in the three-dimensional Calderón inverse conductivity problem can be reduced to the study of the inverse boundary problem of a Schrödinger operator with a real potential. Due to the lack of a rigorous definition, the Born approximation has been relegated to a marginal place in the reconstruction problem. In this talk we will introduce the Born approximation for Schrödinger operators in the ball, which amounts to studying the linearization of the inverse problem. We first analyze this approximation for real and radial potentials in any dimension >2.

Nom de l'orateur
Marcel Guardia Munarriz
Etablissement de l'orateur
Universitat Politècnica de Catalunya (UPC)
Lieu de l'exposé
salle des séminaires
Date et heure de l'exposé

Breathers are temporally periodic and spatially localized solutions of evolutionary PDEs. They are known to exist for integrable PDEs such as the sine-Gordon equation, but are believed to be rare for general nonlinear PDEs. When the spatial dimension is equal to one, exchanging the roles of time and space variables (in the so-called spatial dynamics framework), breathers can be interpreted as homoclinic solutions to steady solutions and thus arise from the intersections of the stable and unstable manifolds of the steady states.

Nom de l'orateur
Hao Zhang
Etablissement de l'orateur
Université de Besançon
Lieu de l'exposé
salle des séminaires
Date et heure de l'exposé
Recently, Quanhua Xu has shown the optimal orders of the Littlewood-Paley-Stein inequality and raised the problem about the optimal orders of the reverse Littlewood-Paley-Stein inequality. In a joint work with Zhendong Xu, we solve one part of Xu's open problem. In this talk, I will recall the history and recent developments of the Littlewood-Paley-Stein theory. Then I will show our proof by using the Burkholder-Gundy inequality.
Nom de l'orateur
Marina Iliopoulou
Etablissement de l'orateur
University of Birmingham
Lieu de l'exposé
salle des séminaires
Date et heure de l'exposé

This is a conjecture on weighted estimates for the classical Fourier extension operators of harmonic analysis. In particular, let E be the extension operator associated to some surface, and g be a function on that surface. If we 'erase' part of Eg, how well can we control the 2-norm of the remaining piece? The Mizohata-Takeuchi conjecture claims some remarkable control on this quantity, involving the X-ray transform of the part of the support of Ef that we kept. In this talk we will discuss the basics and history of the problem, as well as some small progress.

Nom de l'orateur
Tomasz Pełka
Etablissement de l'orateur
Basque Center for Applied Mathematics
Lieu de l'exposé
Salle Éole
Date et heure de l'exposé

I will present my recent joint work with J. F. de Bobadilla, proving that a family of isolated hypersurface singularities with constant Milnor number has constant multiplicity. The key idea is to endow the A'Campo model of "radius zero" monodromy with a symplectic structure. More precisely, I will construct a smooth manifold, fibered over an annulus, together with a fiberwise symplectic form such that the following holds. Over the outer circle ("positive radius"), we get the usual Milnor fibration.

Nom de l'orateur
Itamar Oliveira
Etablissement de l'orateur
Cornell University
Lieu de l'exposé
zoom
Date et heure de l'exposé

The goal of the talk is to motivate and introduce the main questions regarding the Fourier restriction operator for the paraboloid, as well as to present some recent developments that we obtained in joint work with Camil Muscalu. We will describe some connections between the study of this operator and questions in dispersive PDEs and geometric measure theory.

Nom de l'orateur
Lars Sektnan
Etablissement de l'orateur
University of Gothenburg
Lieu de l'exposé
Salle des séminaires
Date et heure de l'exposé

Extremal Kähler metrics were introduced by Calabi in the 80’s as a type of canonical Kähler metric on a Kähler manifold, and are a generalisation of constant scalar curvature Kähler metrics in the case when the manifold admits automorphisms. A natural question is when the blowup of a manifold in a point admits an extremal Kähler metric. We completely settle the question in terms of a finite dimensional moment map/GIT condition, generalising work of Arezzo-Pacard, Arezzo-Pacard-Singer and Székelyhidi.