Noticias en español
Seminars appear in decreasing order in relation to date. To find an activity of your interest just go down on the list. Normally seminars are given in English. If not, they will be marked as Spanish Only.
Particle systems and propagation of chaos for some kinetic models
Abstract: In this talk we will make a quick historical review of some equations arising in the classical kinetic theory of gases and related models. We will start with the Boltzmann equation, which describes the evolution of the distribution of positions and velocities of infinitely many small particles of a gas in 3-dimensional space, subjected to elastic binary collisions. We consider a finite $N$-particle system and introduce the important concept of propagation of chaos: the convergence, as $N\to\infty$ and for each time $t\geq 0$, of the...
Negative Prices in Stackelberg Network Pricing Games.
Abstract: A Stackelberg network pricing game is a two-stage game, in which, in the first stage, a leader sets prices/tolls for a subset of edges so as to maximize profit (all other edges have a fixed cost), and, in the second stage, one or multiple followers choose a shortest path from their source to sink. Labbé et al. (1998) showed that finding optimal prices with lower bounds is NP-hard and gave an example in which profit is maximized by using negative prices. We explore this last phenomena and study the following two questions already...
La argumentación en el aula de matemáticas como parte del desarrollo de la autonomía intelectual.
Resumen: En la presentación daré algunas luces acerca de algunos modos de concebir la argumentación en el aula de matemáticas (y fuera de ella, de paso). Enmarcaré estas ideas sobre argumentación, entre otras, sobre autonomía intelectual, con el fin de ponerla en la perspectiva de argumentación para la ciudadanía. Con este andamiaje teórico, expondré algunos resultados obtenidos observando aulas de matemáticas de educación media.
A characterization of well-posedness for abstract Cauchy problems with finite delay
In this talk, we characterize the mildly well-posedness of the first order abstract Cauchy problem with finite delay, solely in terms of a strongly continuous one-parameter family of bounded linear operators that satisfies a novel functional equation. In the case that the delay operator is null, this property is reduced to characterize the well-posedness of the first order abstract Cauchy problem in terms of the Abel’s functional equation that satisfies a C0- semigroup.
Lp-estimates for nonlocal in time heat kernels
Abstract: In [1] and [2], the authors study independently the so called fully nonlocal diffusion equation, which is of fractional order both in space and time. In both papers, the authors need several technical results about the so-called Mittag-Leffler functions and Fox H-functions to obtain Lp-estimates of the solutions. This approach seems not to be very helpful (or easy) to derive the Lp-estimates of solutions to equations with other nonlocal in time operators (for example sums of fractional derivatives). In this talk, we present a...
Multidimensional continued fractions and symbolic dynamics for toral translations
ABSTRACT: We give a dynamical, symbolic and geometric interpretation to multi-dimensional continued fractions algorithms. For some strongly convergent algorithms, the construction gives symbolic dynamics of sublinear complexity for almost all toral translations; it can be used to obtain a symbolic model of the diagonal flow on lattices in $\mathbb R^3$.
Convergence of projection algorithms: some results and counterexamples.
Abstract: Projection methods can be used for solving a range of feasibility and optimisation problems. Whenever the constraints are represented as the intersection of closed (convex) sets with readily implementable projections onto each of these sets, a projection based algorithm can be employed to force the iterates towards the feasible set. Some versions of projection methods employ approximate projections; one can also consider under- and over-relaxed iterations (such as in the Douglas-Rachford method). In this talk I will focus on...
Two-time distribution for KPZ growth in one dimension
Abstract: Consider the height fluctuations H(x,t) at spatial point x and time t of one-dimensional growth models in the Kardar-Parisi-Zhang (KPZ) class. The spatial point process at a single time is known to converge at large time to the Airy processes (depending on the initial data). The multi-time process however is less well understood. In this talk, I will discuss the result by Johansson on the two-time problem, namely the joint distribution of (H(x,t),H(x,at)) with a>0, in the case of droplet initial data. I also show how to...
Linear inviscid damping and enhanced viscous dissipation of shear flows by the conjugate operator method
Abstract: We will show how we can use the classical Mourre commutator method to study the asymptotic behavior of the linearized incompressible Euler and Navier-Stokes at small viscosity equations about shear flows. We will focus on the case of the mixing layer. Joint work with E Grenier, T. Nguyen and A. Soffer
Intertwinings and Stein’s factors for birth-death processes
Abstract: In this talk, I will present intertwinings between Markov processes and gradients, which are functional relations relative to the space-derivative of a Markov semigroup. I will recall the first-order relation , in the continuous case for diffusions and in the discrete case for birth-death processes, and introduce a new second-order relation for a discrete Laplacian. As the main application, new quantitative bounds on the Stein factors of discrete distributions are provided. Stein’s factors are a key component of Stein’s method, a...
