Seminars of LAMA

Four regular seminars take place at LAMA, in the seminar room, first floor of the building Le Chablais, (see How to come ?).

Weekly seminars:

Others seminars

Next seminars:

EDPs²Friday 31st March 2023 at 14h Marie Amélie Morlais (Université du Maine),
Optimal switching problems and related systems of PDEs with (interconnected) obstacles.

Abstract: (Hide abstracts)
This talk shall focus on the presentation of a (by now) well studied research topic in the field of stochastic control theory, i.e the case of optimal switching control problems. A main objective of this talk is to provide the connection with system of semilinear PDEs with obstacles which, in addition, are inter- connected. This last feature (among some others) explains why the solution is not smooth (in general). For this reason we study existence and uniqueness of solutions of these PDEs in viscosity sense. In a first part, we shall explain the relationship between the value functional associated with a stochastic control problem and the solution of an explicit semi- linear PDE. For this, we need to introduce both the stochastic framework and some advanced probabilistic tools & technics. Next and after this introductory part, we shall give the precise structure of the system of PDEs we are interested in and provide some theoretical results. If time allows, the last slides present the main steps of one of our main results. This talk is based on several joint works (with Pr. S. Hamadène (LMM), Pr. B Djehiche (KTH Stockholm) and X. Zhao former pHD student at the LMM).

GéométrieThursday 21st September 2023 at 14h Dimitri Wyss (EPFL Lausanne),
À venir

Abstract: (Hide abstracts)
À venir

LIMDThursday 6th April 2023 at 10h Damien Pous (Lyon),
Reductions for Kleene algebra with top (jww Jana Wagemaker, after discussions with Paul Brunet, Amina Doumane & Jurriaan Rot)

Abstract: (Hide abstracts)
We will prove two completeness results for Kleene algebra with a top element, with respect to languages and binary relations. While the equational theories of those two classes of models coincide over the signature of Kleene algebra, this is no longer the case when we consider an additional constant ``top'' for the full element. Indeed, the full relation satisfies more laws than the full language, and we show that those additional laws can all be derived from a single additional axiom. The proofs combine models of closed languages, reductions, a bit of graphs, and a bit of automata.