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.
2026
- July 14 10.30, sala conferenze INdAM (TBC) Piazzale Aldo Moro, 5 – Roma
Raphaël Chétrite
LYSM
TBA
- July 7 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma
Gaëtan Fournier
LYSM
TBA
- May 5 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma
Emiliano Ambrosi
LYSM
TBA
- April 7 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma
Giacomo Cherubini
INdAM & Dipartimento di Matematica Guido Castelnuovo Sapienza Università di Roma
TBA
- March 3 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma
Alberto Grillo (TBC)
Université Paris-Panthéon-Assas
TBA
- February 3 10.30, sala di consiglio Dipartimento di Matematica Guido Castelnuovo Sapienza Università di Roma
Radu Ignat
LYSM
Symmetry of domain walls in Ginzburg-Landau type systems
Abstract: Domain walls are topological solitons that appear in many
physical systems (phase transitions, condensed matter etc). They
represent transition layers between two states corresponding to the
wells of a certain potential function. We will start by presenting the
domain walls in the Allen-Cahn model where the potential has a finite
number of wells; in particular, we will study their symmetry and energy
level. Next we study the case of Ginzburg-Landau type models where the
potential has a continuum of wells. For well-posedness, the
divergence-free constraint is imposed on the order parameter. In this
case, we will study one-dimensional symmetry of domain walls as well as
the nucleation of microstructures according to the shape of the
potential function.
2025
- December 2 17.00, CAREFUL EXCEPTIONAL LOCATION AND SCHEDULE, sala di consiglio Dipartimento di Matematica Guido Castelnuovo Sapienza Università di Roma
Laurent Niederman
LYSM
Generic quasi-periodic co-orbital motions in the planetary three-body problem
Abstract: Numerous orbits in the solar system and in astrodynamics exhibit very peculiar motions. Their common feature is that they involve two moons or satellites orbiting around a much heavier central attractor with almost equal semi-major axes, this is called a co-orbital motion. Despite analytical theories and numerical investigations showing their long-term stability, very few rigorous results in this direction have been obtained so far. In the considered case, there is a singularity which prevents the application of standard perturbation theory for the three-body problem.
Adapting classical ideas of Arnold (1963) in this context and, more specifically, by applying KAM theory to the planar three-body problem, we provide a rigorous proof of the existence of a large measure set of invariant tori supporting quasi-periodic co-orbital motions, hence stable over infinite times.
- November 4 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma
Laura Capuano
Dipartimento di Matematica e Fisica, Università di Roma 3
A journey through continued fractions
Abstract: The continued fraction expansion of a real number is a very efficient tool for finding its best rational approximation. Moreover, continued fractions occur both in many theoretical questions in number theory, complex analysis, dynamical systems, as well as in more practical questions related for example to cryptography. After giving an introduction to the classical theory of continued fractions in the field of real numbers and to famous results and open problems in this setting, I will explain how this theory can be generalized to other worlds, for example to the field of p-adic numbers, where many differences with the classical case arise.
- October 7 10.30 CAREFUL EXCEPTIONAL LOCATION, sala di consiglio Dipartimento di Matematica Guido Castelnuovo Sapienza Università di Roma
Mario Pulvirenti
Dipartimento di Matematica Guido Castelnuovo Sapienza Università di Roma
Kinetic Limit of particle systems
Abstract: How to conciliate the microscopic and macroscopic mathematical description of physical systems? We discuss the Boltzmann work in a modern perspective with a special focus on the rigorous derivation of his equation from the equations of particle systems. We also comment the Hilbert VI problem (1900).
- July 1rst 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma
Gabriella Puppo
Dipartimento di Matematica Guido Castelnuovo Sapienza Università di Roma
Walking with long strides
Abstract: The talk will be on why and how one may want to use large time steps to integrate a PDE
- June 3 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma
Guido Carlet
Institut de Mathématiques de Bourgogne, Dijon France
From the Givental descendent potential for Hurwitz-Frobenius manifolds to Hirota and Lax equations: looking for the Dubrovin-Zhang hierarchies
Abstract: We review some topics in the quest for the integrable hierarchies governing the generating functions of certain enumerative invariants: from the seminal result of Witten-Kontsevich, to the Givental quantization formula for the total descendent potential, to the Givental-Milanov-Tseng scheme to derive the associated Hirota equations. We will focus on some recent results concerning the total descendent potential of a class of genus-zero Hurwitz-Frobenius manifolds.
- May 6 10.30 CAREFUL EXCEPTIONAL LOCATION, sala di consiglio Dipartimento di Matematica Guido Castelnuovo Sapienza Università di Roma
Lucia Caramellino
Dipartimento di Matematica, Università di Roma “Tor Vergata”
Regularization lemmas and applications
Abstract: The talk focuses on some regularization results that allow one to prove estimates in the total variation distance, typically by upgrading already known estimates holding in the Wasserstein distance. In all this, tools from Malliavin calculus will play a crucial role. Some applications will then be discussed.
- April 1rst 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma
Isabeau Birindelli
Dipartimento di Matematica Guido Castelnuovo Sapienza Università di Roma
To be or not to be: A bonfire of Liouville theorems
Abstract: The dichotomy between existence and non existence of entire solutions is a key tool in many contests. We will give an overview of some classical and new results both for local and non local equations at the edge of ellipticity.
- March 4 10.30, sala conferenze INdAM Piazzale Aldo Moro, 5 – Roma
Xavier Venel
Luiss University Rome
Uniform value in stochastic games
Abstract: I will present an introduction to the literature on dynamic problem s controled by several agents, called Stochastic games and in particular on the concept of uniform value (two-player zero-sum case). We will first review the positive results of the literature if the players observe everything before investigating the many difficulties that appear when the players do not observe everything but only some signals.
- 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