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 24th March 2023 at 10h45 Francois Nicot (Univ Savoie Mont-Blanc),
Failure in geomaterials: an emerging process through successive scales

Abstract: (Hide abstracts)
Solving boundary value problems requires implementation of sufficiently robust constitutive models. Most models try to incorporate a great deal of phenomenological ingredients, but this refining often leads to overcomplicated mathematical formulations, requiring a large number of parameters to be identified. On the other hand, geomaterials are known to have an internal microstructure, made up of an assembly of interacting particles. Most of the macroscopic properties, observed on a specimen scale or even on larger scales, mainly result from the microstructural arrangement of grains. Thus, a powerful alternative can be found with micromechanical models, where the medium is described as a distribution of elementary sets of grains. The inherent complexity is not related to the local constitutive description between particles in contact, but to the basic topological complexity taking place within the assembly. This presentation discusses this issue, highlighting very recent results obtained from discrete element simulations. In particular, the so-called critical state regime that develops during localized or diffuse failure is discussed in detail from the perspective of emerging processes taking place within complex media.

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.