Pagina 28

Date | Type | Start | End | Room | Speaker | From | Title |
---|---|---|---|---|---|---|---|

11/03/22 | Seminario | 14:30 | 15:30 | 1201 Dal Passo | University of Copenhagen | Algebra & Representation Theory Seminar (ARTS) "Symmetric groups, Hurwitz spaces and moduli spaces of surfaces" - in live & streaming mode - ( please
click HERE to attend the talk in streaming ) this talk is part of the activity of the MIUR Excellence Department Project CUP E83C18000100006N.B.: | |

08/03/22 | Seminario | 14:30 | 15:30 | 1201 Dal Passo | Matilde Manzaroli | Geometry SeminarA morphism of smooth varieties of the same dimension is called
real fibered if the inverse image of the real part of the target is the
real part of the source. It goes back to Ahlfors that a real algebraic
curve admits a real fibered morphism to the projective line if and only
if the real part of the curve disconnects its complex part. Inspired by
this result, in a joint work with Mario Kummer and Cédric Le Texier, we
are interested in characterising real algebraic varieties of dimension n
admitting real fibered morphisms to the n-dimensional projective space.
We present a criterion to construct real fibered morphisms that arise as
finite surjective linear projections from an embedded variety; this
criterion relies on topological linking numbers. We address special
attention to real algebraic surfaces. We classify all real fibered
morphisms from real del Pezzo surfaces to the projective plane and
determine when such morphisms arise as the composition of a projective
embedding with a linear projection. | |

01/03/22 | Seminario | 16:00 | 17:00 | 1201 Dal Passo | Pierre Cardaliaguet | Université Paris Dauphine | Seminario di Equazioni Differenziali On the convergence rate for the optimal control of McKean-Vlasov
dynamics
(MS Teams link for the streaming at the end of the abstract) In this talk I will report on a joint work with S. Daudin (Paris Dauphine), Joe Jackson (U. Texas) and P. Souganidis (U. Chicago). We are interested in the convergence problem for the optimal control of McKean-Vlasov dynamics, also known as mean field control. We establish an algebraic rate of convergence of the value functions of N-particle stochastic control problems towards the value function of the corresponding McKean-Vlasov problem. This convergence rate is established in the presence of both idiosyncratic and common noise, and in a setting where the value function for the McKean-Vlasov problem need not be smooth. Our approach relies crucially on Lipschitz and semi-concavity estimates, uniform in N, for the N-particle value functions, as well as a certain concentration inequality.
MS Teams Link for the streaming
Note:
This talk is part of the activity of the MIUR Department of Excellence Project MATH@TOV CUP E83C18000100006 |

01/03/22 | Seminario | 14:30 | 15:30 | 1201 Dal Passo | Emanuele Macrì | Geometry Seminarclick here to attend the talk in streaming (MS Teams)]We will present joint work with Olivier Debarre, Daniel Huybrechts and
Claire Voisin on the SYZ hyper-Kähler conjecture for fourfolds under
certain topological assumptions.
As application, this proves a conjecture by O'Grady that a
hyper-Kähler fourfold whose cohomology ring is isomorphic to the one
of the Hilbert square of a K3 surface is a deformation of a Hilbert
square. | |

25/02/22 | Seminario | 16:00 | 17:00 | 1201 Dal Passo | Università di Firenze | Algebra & Representation Theory Seminar (ARTS) "On Sylow Branching Coefficients" - in live & streaming mode -
( please click
HERE to attend the talk in streaming ) In this talk we will discuss the nature of the relationship between the representations of a finite group G and those of a Sylow subgroup P of G. We will introduce Sylow Branching Coefficients (SBCs) and we will show how the study of these numbers led us to prove a conjecture proposed by Malle and Navarro in 2012. We will conclude by presenting new results on SBCs in the case where G is the symmetric group. The talk is based on joint works with Law, Long, Navarro, Vallejo and Volpato. N.B.: please click HERE to attend the talk in streaming.
| |

25/02/22 | Seminario | 14:30 | 15:30 | 1201 Dal Passo | Università di Bologna | Algebra & Representation Theory Seminar (ARTS) "Fully commutative elements and spherical nilpotent orbits" - in live & streaming mode -
( please click
HERE to attend the talk in streaming ) Let g be a simple Lie algebra, with a fixed Borel subalgebra b = t+n , and let W be the associated Weyl group. The Steinberg map associates to any element of W a nilpotent orbit in g, which is defined by the corresponding set of inversions. Extending on previous work of Fan and Stembridge, in this talk I will compare two different notions of "smallness", one available in the Weyl group and the other one for nilpotent orbits. N.B.: please click HERE to attend the talk in streaming.
| |

22/02/22 | Seminario | 16:00 | 17:00 | 1201 Dal Passo | Cristian Mendico | Università di Roma | Seminario di Equazioni Differenziali Asymptotic behavior of solutions to Hamilton-Jacobi-Bellmann equations
(MS Teams link for the streaming at the end of the abstract) The analysis of the ergodic behavior of solutions to Hamilton-Jacobi-Bellmann equations has a long history going back to the seminal paper by [Lions, P.-L., Papanicolaou, G. and Varadhan, S.R.S]. Since this work, the subject has grown very fast and when the Hamiltonian is of Tonelli type a large number of results have been proved. A full characterization of the ergodic behavior of solutions to Tonelli Hamilton-Jacobi equations can be found in the celebrated weak KAM theory and Aubry-Mather theory. However, few results are available if the Hamiltonian fails to be Tonelli, i.e.,
the Hamiltonian is neither strictly convex nor coercive with respect to the momentum variable. In particular, such results cover only some specific structure and so, the general problem is still open. In this talk, I will present some recent results obtained in collaboration with Piermarco Cannarsa and Pierre Cardaliaguet concerning the long time-average behavior of solutions to Hamilton-Jacobi-Bellman equations. We will look, first, to the case of control of acceleration and, then, to sub-Riemannian control systems. Finally, we conclude
this talk showing how the previous analysis applies to mean field game systems.
MS Teams Link for the streaming
Note:
This talk is part of the activity of the MIUR Department of Excellence Project MATH@TOV CUP E83C18000100006 |

22/02/22 | Seminario | 14:30 | 15:30 | 1201 Dal Passo | Roberto Fringuelli | Geometry SeminarLet G be a complex (connected) reductive group and C be a complex smooth projective curve of genus at least four. It is known that the moduli space of semistable G-bundles over C is a projective variety. The automorphism group of this variety contains the so-called tautological automorphisms: they are induced by the automorphisms of the curve C, outer automorphisms of G and tensorization by Z-torsors, where Z is the center of G. It is a natural question to ask if they generate the entire automorphism group. Kouvidakis and Pantev gave a positive answer when G=SL(n). An alternative proof has been given by Hwang and Ramanan. Later, Biswas, Gomez and Muñoz, after simplifying the proof for G=SL(n), extended the result to the symplectic group Sp(2n). All the proofs rely on the study of the singular fibers of the Hitchin fibration. In this talk, we present a recent work where, by adapting the Biswas-Gomez-Muñoz strategy, we describe the automorphism group of the connected components of the moduli space of semistable G-bundles over C, for any almost-simple group G. | |

15/02/22 | Seminario | 16:00 | 17:00 | 1201 Dal Passo | Nicolas Augier | CNRS-LAAS, Toulouse | On the use of quasi-static controls and duplication of controls for quantum systems
( MS Teams Link for the streaming )
In a first part of the talk, I will present some geometric techniques allowing to control quantum systems using slowly-varying controls, in the so-called adiabatic regime. The latter provides strong control results only when the system is driven by at least two controls, which is a strong requirement in practice. The second part of the talk will be dedicated to an averaging approximation (Rotating Wave Approximation) which allows to duplicate controls in this setting. NB:This talk is part of the activity of the MIUR Excellence Department Project MATH@TOV CUP E83C18000100006 |

15/02/22 | Seminario | 14:30 | 15:30 | 1201 Dal Passo | Luca De Feo | Geometry SeminarClick here to attend the talk in Streaming (MS Teams Link)]Le isogenie sono morfismi di varietà abeliane. La loro teoria algoritmica è sviluppata da oltre 30 anni, motivata in parte dall'algoritmo di Schoof-Elkies-Atkin per il conteggio di punti, algoritmo fondamentale in crittografia ellittica. I progressi algoritmici hanno portato negli ultimi 20 anni allo sviluppo di una nuova branca della crittografia, detta a base d'isogenie. L'oggetto centrale di questa disciplina non è più una curva ellittica isolata, bensì un grafo di curve ellittiche legate da isogenie. I grafi d'isogenie esibiscono diverse strutture combinatorie interessanti (foreste, grafi di Cayeley, grafi espansori), e offrono dei problemi computazionalmente difficili come la ricerca di cammini. Su queste basi, siamo oggi in misura di costruire un vasto spettro di primitive crittografiche: cifratura e firma digitale resistenti agli attacchi quantistici, crittografia a orologeria, sistemi a soglia, ecc. In questo talk, darò un'introduzione alla teoria delle isogenie di curve ellittiche su corpi finiti, e spiegherò come la crittografia è costruita a partire da esse. |

<< 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 >>