Sala Riunioni (Dip. Matematica)

On type-preserving representations of the four-punctured sphere group

Tipo Seminario: 
Relatore: 
Tian Yang

We give counterexamples to a conjecture of Bowditch that if a non-elementary
type-preserving representation ρ : π1(Σg,n) → P SL(2; R) of a punctured surface
group sends every non-peripheral simple closed curve to a hyperbolic element,
then ρ must be Fuchsian. The counterexamples come from relative Euler class
±1 representations of the four-punctured sphere group. As a related result, we
show that the mapping class group action on each non-extremal component of the
character space of type-preserving representations of the four-punctured sphere

Data Seminario: 
Wednesday, June 26, 2019
Aula: 
Sala Riunioni (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 16:00
Affiliazione: 
Texas A&M University
Ora Inizio: 
Saturday, January 1, 0000 - 15:00

A semilinear curl-curl problem in R^3

Relatore: 
Jacopo Schino

SEMINARIO MAP:

We look for nontrivial solutions to the semilinear elliptic problem: 

\nabla\times \nabla\times u = f(x,u)

Data Seminario: 
Monday, June 24, 2019
Aula: 
Sala Riunioni (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 18:00
Affiliazione: 
Institute of Mathematics, Polish Academy of Sciences
Ora Inizio: 
Saturday, January 1, 0000 - 16:30

Interacting Particle Systems in Random Environment and PDEs

Relatore: 
Simone Floreani

SEMINARIO MAP: 

In this talk we will derive the diffusion equation starting from a microscopic description of a system of interacting particles in an inhomogeneous media. The dynamics of the particle system will be stochastic and, more precisely, Markovian. However, due to the non-trivial interaction which particles undergo, the evolution of each particle is not Markovian in itself.  

Data Seminario: 
Friday, June 21, 2019
Aula: 
Sala Riunioni (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 18:00
Affiliazione: 
Technische Universiteit Delft
Ora Inizio: 
Saturday, January 1, 0000 - 16:30

Smooth Reifenberg theorems for sets and measures

Relatore: 
Silvia Ghinassi

Abstract. We provide geometric sufficient conditions for one-sided Reifenberg flat sets of any integer dimension in Euclidean space to be parametrized by a Lipschitz map with Hölder derivatives. The conditions use a Jones type square function and all statements are quantitative in that the Hölder and Lipschitz constants of the parametrizations depend on such a function.
We use these results to prove sufficient conditions for higher order rectifiability of sets and measures.

Data Seminario: 
Wednesday, June 19, 2019
Aula: 
Sala Riunioni (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 18:00
Affiliazione: 
Institute for Advanced Study, Princeton
Ora Inizio: 
Saturday, January 1, 0000 - 17:00

Rank structures in matrix equations and matrix functions

Relatore: 
Leonardo Robol

Low-rank matrices (and tensors) appear often in applications, and this can
be exploited in several ways to treat large scale problems that would be otherwise
unfeasible. It has been known since a long time that in some applications, such
as the solution of the Sylvester equation AX + XB + C = 0, working with
low-rank C often leads to a solution X which is full rank, but can be efficiently
approximated by a low-rank matrix. This can be used, among other things, in
solving PDEs defined by separable operators, such as the 2D Laplace operator

Data Seminario: 
Wednesday, June 5, 2019
Aula: 
Sala Riunioni (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 15:30
Affiliazione: 
Dipartimento di Matematica, Università di Pisa
Ora Inizio: 
Saturday, January 1, 0000 - 14:30

The renormalized energy for a system of edge dislocations with multiple Burgers vectors

Relatore: 
Marco Bresciani

Dislocations are 1-dimensional defects of the crystal lattice and their motion is considered the main cause of plastic deformations in metals. In this talk, we study a variational model that describes a system of straight and parallel edge dislocations in an elastic body. These are represented by singularity points of the strain fields, which are defined on a cross-section orthogonal to the dislocation lines. In the analysis, we adopt the so-called core-region approach.

Data Seminario: 
Monday, May 6, 2019
Aula: 
Sala Riunioni (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 18:00
Affiliazione: 
Università di Pavia
Ora Inizio: 
Saturday, January 1, 0000 - 16:30

L' entropia centrale dei polinomi quadratici

Relatore: 
Giulio Tiozzo

La nozione di entropia topologica, derivante dalla teoria dell'informazione,
è uno strumento fondamentale per comprendere la complessità di un sistema dinamico.
Quando il sistema dinamico varia in una famiglia, sorge naturalmente la domanda:
come varia l'entropia al variare del parametro?

Recentemente, W. Thurston ha introdotto queste idee in dinamica complessa definendo l’ "entropia centrale" di
un polinomio quadratico come l'entropia di un certo sottoinsieme dell'insieme di Julia (l'albero di Hubbard).

Data Seminario: 
Thursday, May 23, 2019
Aula: 
Sala Riunioni (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 15:30
Affiliazione: 
Toronto U.
Ora Inizio: 
Saturday, January 1, 0000 - 14:30

Density Functional Theory and Optimal Transport: Seidl Gori-Giorgi Savin conjectures and continuity

Relatore: 
Simone di Marino

In recent times, density functional limit in the strctly correlated regime has been identified as a multimarginal optimal transport problem by Seidl, Gori-Giorgi, Savin, where they conjectured the existence of explicit optimal maps. We provide positive results in the one dimensional case as well as both positive and negative results in the radial 2-dimensional case. We establish also the maximal domain of finiteness and continuity of the energy with respect to the measure.

Data Seminario: 
Monday, April 29, 2019
Aula: 
Sala Riunioni (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 17:00
Affiliazione: 
SNS
Ora Inizio: 
Saturday, January 1, 0000 - 16:00

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