Les adhésines cellulaires : variations sur un thème

Variations sur un THème de Aldama et Shelah

We study the definability of certain subgroups of a group G that does not have the independence property. If a (type) definable subset X of an elementary extension G of G has property P , we call its trace X∩G over G an externally (type) definable P set. We show the following. Centralisers of subsets of G are externally definable subgroups. Cores of externally definable subgroups and iterated c...

Un système X Raisonner formellement sur les programmes ML

Résumé Nous proposons dans cet article un système de types dit renforcé permettant de garantir la terminaison de programmes exprimés dans le noyau fonctionnel pur de ML. La stratégie d'évaluation est celle de ML. Le langage de types est celui de ML. Le caractère renforcé du système proposé vient de l'ajout aux règles de typage traditionnelles d'un principe d'induction structurelle sur les types...

Zéro-cycles de degré un sur les espaces homogènes

We explain how to build homogeneous spaces of a connected linear algebraic group, having zero-cycles of degree one but no rational point, even on a smooth compactification. Thus, we give a negative answer to a recent question asked by Burt Totaro. Parimala ([Pa]) has independently produced such spaces over fields of the type k((t)) (for k a suitable p-adic field), which are projective varieties...

Un nouvel algorithme de consistance locale sur les nombres flottants

Solving constraints over floating-point numbers is a critical issue in numerous applications notably in program verification. Capabilities of filtering algorithms over the floating-point numbers have been so far limited to 2b-consistency and its derivatives. Though safe, such filtering techniques suffer from the well known pathological problems of local consistencies, e.g., inability to efficie...

Un outil d'aide à l'installation d'UNIX fondé sur les connaissances