LYSeMinar

LYSeMinar, the seminar of LYSM, will take place once a month in various Roman locations. It is a general seminar open to all, whose speakers will often, but not only, come from the “pool” of beneficiaries of missions financed by the LYSM.

2025

  1. February 4 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma A

Special issue of LYSeMinar: MATINÉE QUANTIQUE

10.30: Alessandro Giuliani “Electrical transport in 2D systems of interacting electrons: the Hall conductivity of the Haldane-Hubbard model”

11.15: Frédéric Patras “Quantum probability and free probability”

12.00: Thierry Paul “Quantum Wasserstein, quantization and calculus of variations

12.45 Lorenzo Tortora de Falco “Logic and interaction, a new IRN of CNRS”

13.00 LUNCH after a few aperitif words by CNRS Mathématiques

  • January 14 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma

Loïc Foissy

LMPA, Calais

Double bialgebra of noncrossing partitions

Abstract : In this talk, we will present a double bialgebra structure on the symmetric algebra generated by noncrossing partitions. The first coproduct is given by the separations of the blocks of the partitions, with respect to the entanglement, and the second one by fusions of blocks. This structure implies that there exists a unique polynomial invariant on noncrossing partitions which respects both coproducts: we will give some elements on this invariant, and applications to the antipode of noncrossing partitions.

2024

  • December 3 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma

Jean-Luc Sauvageot

IMJ-PRG, Paris

From classical fractal sets to self similar C*-algebras: A constructive approach to fractals, commutative and not commutative

Abstract :We review various notions of self-similar fractal compact sets such as Hutchinson’s, Kigami’s or Kamiyama’s, and see which way most of them can be reached through an inceasing sequence of approximating compact sets. This leads to the definition of a similarity scheme, then of the associated similarity functor, both in the classical and the non commutative workframe. We finally define a self-similar C*-algebra as a fixed point of the similarity functor.
We show then how, to any similarity scheme, is associated a projective sequence of C*-algebras, which heuristically tends to self-similarity. We show how it is possible to define a natural projective limit to such a sequence and we provide easy criteria for this limit arising without loss of information. Which will provide a self-similar C*-algebra naturally associated with the similarity scheme we started with. Examples will include new examples of self-similar sets and C*-algebras.

This is a joint work in progress with Fabio Cipriani, Daniele Guido and Tommaso Isola.

  • November 5 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma

Sergio Simonella

Dipartimento di Matematica, Università di Roma “La Sapienza”

Microscopic derivation of a fluctuating hydrodynamics

Abstract: We consider deterministic, time-reversible dynamics with random initial data, in a low-density scaling. Under suitable assumptions on the initial measure, a strong chaos prop- erty is propagated in time, which also encodes the transition to irreversibility. This result is complemented by a theory of fluctuations, allowing to establish the connection between microscopic and hydrodynamic scales, at least for perturbations of a global equilibrium. Many of the open problems left require a deeper understanding of the coupling mechanisms between deterministic and stochastic dynamics. Funded by the European Union 

  • October 1 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma

Frédéric Patras

LYSM, Rome

Algebra and probability: old and new

Abstract: The talk will survey various aspects of the manifold interactions between algebra and probability, starting from Poincaré’s insights on card shuffles till recent advances on the structures underlying quantum probabilities and their applications.

  • September 3 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma

Michela Procesi

Dipartimento di Matematica e Fisica, Università di Roma 3

Maximal tori in infinite dimensional dynamical systems

Abstract: I shall discuss  the existence of infinite-dimensional invariant tori in a mechanical system made of infinitely many rotators weakly interacting with each other. I shall concentrate on interactions depending only on the angles, with the aim of discussing in a simple case the analyticity properties to be required on the perturbation of the integrable system in order to ensure the persistence of a large measure set of invariant tori with finite energy.

Brindisi

après le séminaire, un verre de prosecco sera servi pour fêter le troisième anniversaire du LYSM

al termine del seminario verrà servito un bicchiere di prosecco per festeggiare il terzo anniversario di LYSM

after the seminar, a glass of prosecco will be served to celebrate the third anniversary of LYSM

  • June 4 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma

Adriana Garroni

Dipartimento di Matematica, Università di Roma “La Sapienza”

Variational modelling of grain boundaries

Abstract: I will describe a recent result in collaboration with M. Fortuna and E. Spadaro, based on a model introduce by Lauteri and Luckhaus for the analysis of small angle grain boundaries in crystals. The latter is a semi-discrete model where the elastic distortion of the bulk of the crystal is described by a continuum deformation field and  a small parameter is reminiscent of the lattice spacing of the underlying discrete structure. It also accounts for the crystal symmetry and the presence of defects. In the asymptotic analysis as the lattice spacing tends to zero we recover a sharp interface model for polycrystalline grain boundaries which, for small angles, agrees with the classical Read-Schokley formula.

  • May 7 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma

Eitan Tadmor

University of Maryland and Fondation Sciences Mathématiques de Paris & Laboratoire Jacques-Louis Lions – CNRS – Sorbonne Université/Université Paris Cité

Emergent Behavior in Alignment Dynamics

Abstract: A fascinating aspect of collective dynamics is self-organization of small-scale interactions into high-order structures with larger-scale patterns. In different contexts these are clusters which take the form of flocks, swarms, consensus, synchronized states etc.

In this talk I will survey recent mathematical developments in alignment dynamics, which is driven by the tendency of steering towards average headings. A main question of interest is how different alignment kernels affect the large-crowd, long-time dynamics. We discuss how short- vs. long-range interactions dictate the large-crowd emergent behavior, and the role of pressure away thermal equilibrium