20/02/19  Seminario  14:00  17:00  1101 D'Antoni  Espen SANDE  University of OSLO  An introduction to Kolmogorov nwidths

19/02/19  Seminario  15:30  16:30  1201 Dal Passo  Gilberto Bini  Università di Milano Statale  "Invariants and Classification" [Department Seminar (general audience talk)  in the framework of the Research Project "Families of curves: their moduli and their related varieties"  Mission Sustainability
Tor Vergata, CUP: E8118000100005, Principal Investigator: F. Flamini]
Classification is extremely important in various scientific disciplines, such as Chemistry and Biology, as well as Mathematics. In this talk, we will recall some examples and give some more, specially in relation with projective geometry and birational geometry, in order to give a classification of low dimensional
complex projective varieties with respect to suitable invariants.
Link: http://www.mat.uniroma2.it/~flamini/seminari/annuncio.html
[Department Seminar (general audience talk)  in the framework of the Research Project "Families of curves: their moduli and their related varieties"  Mission Sustainability
Tor Vergata, CUP: E8118000100005, Principal Investigator: F. Flamini] 
19/02/19  Seminario  14:30  15:30  1101 D'Antoni  Benoit FRESSE  Université de Lille  Kontsevich' graph complexes, operadic mapping spaces, and the GrothendieckTeichmüller group
I will report on a joint work with Victor Turchin and Thomas Willwacher about the applications of graph complexes to the study of mapping spaces associated to E_{n}operads.
The class of E_{n}operads consists of objects that are homotopy equivalent to a reference model, the operad of little ndisks, which was introduced by BoardmanVogt in topology. I will briefly review the definition of these objects.
The main goal of my talk is to explain that the rational homotopy of mapping spaces of E_{n}operads has a combinatorial description in terms of the homology of Kontsevich' graph complexes. This approach can also be used for the study of homotopy automorphism spaces associated to E_{n}operads. In the case n=2 , one can identify the result of this computation with the prounipotent GrothedieckTeichmüller group.
The proof of these statements relies on results on the rational homotopy of E_{n}operads which I will also briefly explain in my talk.
N.B.: this talk is part of the activity of the MIUR Excellence Department Project CUP E83C18000100006

13/02/19  Seminario  17:30  18:30  1201 Dal Passo  KarlHermann Neeb  University of ErlangenNürnberg  Finite dimensional endomorphism semigroups of standard subspaces

13/02/19  Seminario  16:00  17:00  1201 Dal Passo  Yoshimichi Ueda  Nagoya University  On Arveson’s boundary theorem
I’ll explain a rather simple proof of Arveson’s boundary theorem by using the notion of Izumi’s noncommutative Poisson boundaries. This talk is based on my joint work with Kei Hasegawa. 
13/02/19  Seminario  14:30  15:30  1201 Dal Passo  Pierre Bieliavsky  Univ. Louvain  On a class of locally compact quantum groups

12/02/19  Seminario  16:00  17:00  1101 D'Antoni  Frank Kutzschebauch  Universita' di Berna  Embedding Riemann surfaces with isolated punctures into C^2
We enlarge the class of open Riemann surfaces known to be holomorphically
embeddable into the plane by allowing them to have additional isolated punctures
compared to the known embedding results.
THEOREM The following open Riemann surfaces admit a proper holomorphic embedding
into C^2:
 the Riemann sphere with a (nonempty) countable closed subset with at most 2
accumulation points removed,
 any compact Riemann surface of genus 1 (torus) with a (nonempty) closed discrete
set with at most one accumulation point removed,
 any hyperelliptic Riemann surface with a discrete closed set C removed with the
properties that C contains a fibre F=R^{1} (p) (consisting either of two points or
a single Weierstrass point) of the Riemann map R and all accumulation points of C
are contained in that fibre F.
The same holds if X is as above with additionally a finite number of smoothly
bounded regions removed.
The second and the third case with no accumulation points in the closed discrete
set correspond to the Theorem of Sathaye.
Joint work with PierreMarie Poloni 
12/02/19  Seminario  14:30  15:30  1201 Dal Passo  Massimiliano Morini  Universita' di Parma  Existence and uniqueness for anisotropic and crystalline mean curvature flows
An existence and uniqueness result, up to fattening, for crystalline mean curvature flows with forcing and arbitrary (convex) mobilities, is proven. This is achieved by introducing a new notion of solution to the corresponding level set formulation. Such solutions satisfy a comparison principle and stability properties with respect to the approximation by suitably regularized problems. The results are valid in any dimension and for arbitrary, possibly unbounded, initial closed sets. As a result of our analysis, we deduce the convergence of a minimizing movement scheme proposed by Almgren, Taylor and Wang (1993), to a unique (up to fattening) “flat flow”.

06/02/19  Seminario  16:00  17:00  1201 Dal Passo  Ken Dykema  Texas A&M University  Schurtype upper triangular forms and decomposability in finite von Neumann algebras
The spectrum of an operator contains essential information. Even better is when we can find invariant subspaces that break the operator into pieces with conditions on the spectrum. This is the meaning of decomposability of an operator, in the sense of Foias.
An arbitrary element of a finite von Neumann algebra has a sort of spectral distribution measure called its Brown measure. Haagerup and Schultz proved existence of invariant subspaces that break up such an
element according to its Brown measure. These HaagerupSchultz subspaces have been used to provide Schurtype upper triangular forms for such elements. In this talk, we review these constructions and describe how these Schurtype upper triangular forms relate to decomposability in the sense of Foias. (Joint with with Joe Noles, Fedor Sukochev, and Dima Zanin). 
06/02/19  Seminario  14:00  16:00  1201 Dal Passo  Edoardo Sernesi  Roma Tre  Curves on K3 Surfaces III [Lecture series in the framework of the Research Project "Families of curves: their moduli and their related varieties"  Mission Sustainability Tor Vergata, CUP: E8118000100005, Principal Investigator: F. Flamini]
 Generalities on BrillNoether theory. Lazarsfeld's proof of Petri's conjecture.  Gaussian maps, ribbons and extendability. Results of Wahl and BeauvilleMerindol.  The problem of characterizing K3 curves: some results.
[Lecture series in the framework of the Research Project "Families of curves: their moduli and their related varieties"  Mission Sustainability Tor Vergata, CUP: E8118000100005, Principal Investigator: F. Flamini] 