Notiziario Scientifico
Notiziario dei seminari di carattere matematico
a cura del Dipartimento 'G. Castelnuovo'
Sapienza Università di Roma
Settimana dal 22 al 28 maggio 2017
Martedì 23 maggio 2017
Ore 14:30, aula Dal Passo, Università di Roma Tor Vergata
seminario di Equazioni Differenziali
Alberto Tesei (Sapienza Università di Roma)
Equazioni paraboliche quasilineari di tipo forward-backward
Discuteremo alcuni recenti risultati su equazioni di tipo forward-backward, con particolare
attenzione alla formazione e scomparsa di singolarità. Le regolarizzazioni usate per
le equazioni sono di tipo pseudoparabolico degenere o di tipo Cahn-Hilliard. I risultati che
esporremo sono stati ottenuti in collaborazione con M. Bertsch, L. Giacomelli e F. Smarrazzo.
Martedì 23 maggio 2017
Ore 14:30, aula D'Antoni, Università di Roma Tor Vergata
seminario di Geometria Algebrica
Paolo Stellari (Università di Milano)
Bridgeland stability for semiorthogonal decompositions and cubic fourfolds
Various interesting results concerning the geometry of smooth cubic threefolds point to the relevance
of constructing Bridgeland stability conditions on semiorthogonal decompositions.
We illustrate some of them and a new method to induce stability conditions on semiorthogonal
decompositions. We prove that it provides Bridgeland stability conditions on the Kuznetsov component
of the derived category of cubic fourfolds. Some geometric applications are discussed.
This is joint work in progress with Arend Bayer, Martì Lahoz and Emanuele Macrì
(and partly with X. Zhao and M. Lehn)
Martedì 23 maggio 2017
Ore 15:00, aula 1B1, dipartimento SBAI
seminario di Geometria
Daniel Labardini-Fragoso (Universidad Nacional Autonoma de Mexico)
Grassmannians and triangulations: an invitation to cluster algebras
The Grassmannian Gr(k,n) is the set of all k-dimensional vector subspaces of a complex
vector space of dimension n. Elementary considerations give rise to the Plücker
embedding of Gr(k,n) in a projective space. The Plücker coordinates satisfy certain
relations whose form for k=2 suggests a parameterization of a generating set through
diagonals and triangulations of a polygon. I will use this example to try and motivate
Fomin-Zelevinsky's definition of cluster algebras.
Mercoledì 24 maggio 2017
Ore 13:00, aula F, Università di Roma Tre, l.go san L. Murialdo 1
presentazione della Laurea Magistrale in Scienze Computazionali
13:00 Presentazione della Laurea Magistrale in Scienze Computazionali e del piano didattico
14:00 Seminari sul Calcolo Scientifico
F. Castiglione (CNR-IAC)
M. Ceseri (Sportello Matematico)
R. D'Autilia (Roma Tre) Realtà e astrazione delle simulazioni numeriche
R. Ferretti (Roma Tre) Dal problema alla soluzione
M. Pedicini (Roma Tre) Modelli per il supercalcolo
Mercoledì 24 maggio 2017
Ore 15:00, aula di Consiglio
seminario di Algebra e Geometria
Emmanuel Letellier (Paris 7)
Computing the Poincaré polynomial of character varieties
In this talk I will review some work with Hausel and Rodriguez-Villegas on the computation of the
Poincaré polynomial of character varieties (moduli space of representations of fundamental
group of punctured Riemann surfaces into GL(n,C)) using arithmetic geometry and the character
table of GL(n) over finite fields.
Mercoledì 24 maggio 2017
Ore 16:15, aula di Consiglio
seminario di Fisica Matematica
Stefan Teufel (Universität Tübingen)
Particle Creation at a Point Source by Means of Interior-Boundary Conditions
We consider a way of defining quantum Hamiltonians involving particle creation and annihilation based
on an interior-boundary condition (IBC) on the wave function, where the wave function is the particle-position
representation of a vector in Fock space, and the IBC relates (essentially) the values of the wave function
at any two configurations that differ only by the creation of a particle. Here we prove, for a model of particle
creation at one or more point sources using the Laplace operator as the free Hamiltonian, that a Hamiltonian
can indeed be rigorously defined in this way without the need for any ultraviolet regularization, and that it is
self-adjoint. We prove further that introducing an ultraviolet cut-off (thus smearing out particles over a positive
radius) and applying a certain known renormalization procedure (taking the limit of removing the cut-off while
subtracting a constant that tends to infinity) yields, up to addition of a finite constant, the Hamiltonian defined
by the IBC.
Giovedì 18 maggio 2017
Ore 14:30, aula 211, Università di Roma Tre,
largo san L. Murialdo 1
seminario di Geometria
David Holmes (University of Leiden)
Fine compactified moduli of enriched structures on stable curves
An 'enriched structure' on a nodal curve over a (separably closed) field is a special collection of line
bundles which combine combinatorial and geometric information. Enriched structures were first
defined in the PhD thesis of Laila Maino, where she also constructed a coarse moduli space.
They have played a role in the study of degenerating jacobians and limit linear series. We will explain
how to define an enriched structure on a nodal curve over an arbitrary base scheme, and construct a
fine moduli stack. We will then explain how to compactify this, by replacing line bundles by suitable
torsion free sheaves. If time allows, we will discuss applications to the double ramification cycle.
This is joint work with Owen Biesel, see arXiv 1607.08835.
Giovedì 25 maggio 2017
Ore 15:00, aula di Consiglio
seminario di Probabilità e Statistica
Ehud Lehrer (Tel Aviv University)
Non-additive probability, integration and decision making
Frequently a decision maker (DM) does not have a full information about the underlying uncertainty.
For instance, the information about the probability of some events might be missing, or the probability
distribution might fail to be additive. In this talk I will present non-additive probabilities, describe a few
methods of integration with respect to these probabilities and how one may use these schemes in
decision making.
Venerdì 26 maggio 2017
Ore 11:00, aula Aula Magna, Università di Firenza, via S. Gallo 10 (Firenze)
A spring day in probability and statistical physics
11.00 R. Fernandez (Utrecht) Signal description: process or Gibbs? I
12.00 R. Fernandez (Utrecht) Signal description: process or Gibbs? II
14.30 R. Morris (IMPA) Monotone cellular automata I
15.30 R. Morris (IMPA) Monotone cellular automata II
Venerdì 26 maggio 2017
Ore 12:00, aula di Consiglio
seminari MoMa
Roberto Di Leonardo
The Physics and Engineering of Active Matter
Dense suspensions of swimming bacteria display striking motions that look extremely vivid
when compared to the thermal agitation of colloidal particles of comparable size. These
suspensions belong to a wider class of non-equilibrium systems that are now collectively
referred to as active matter. Research in active matter physics deals with the fundamental
aspects underlying some distinctive properties of these systems, such as the emergence of
collective behavior and rectification phenomena. From a more engineering perspective, however,
active matter can be looked at as a special kind of fuel: a small droplet of an active fluid
can be used to propel micro-machines inside miniaturized chips, with no need of external
driving fields or control.
Using advanced tools for 3D optical imaging, manipulation and fabrication we study complex
phenomena in active matter with direct and quantitative methods. I will review our recent
work in this direction, from off-equilibrium transport and stationary states in active matter
to the use of genetically engineered bacteria as controllable propellers for synthetic
micro-machines.
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