# Séminaires : Séminaire Général de Logique

 Equipe(s) : lm, Responsables : S. Anscombe, A. Khélif, A. Vignati Email des responsables : sylvy.anscombe@imj-prg.fr, vignati@imj-prg.fr Salle : 1013 Adresse : Sophie Germain Description

 Orateur(s) Chris Laskowski - University of Maryland , Titre Borel complexity and potential canonical Scott sentences Date 26/02/2018 Horaire 15:10 à 16:10 Diffusion Résume Given a first order theory or a sentence $\Phi$ of $L_\omega_1,\omega$, we define the class of potential canonical Scott sentences of $\Phi$. Simply by comparing cardinalities, we obtain new results about the Borel complexity of $(Mod(\Phi),\iso)$, the class of countable models of $\Phi$. In particular, we find examples of first order theories T for which Mod(T) is not Borel complete, yet the isomorphism relation on Mod(T) is not Borel. This is joint work with Douglas Ulrich and Richard Rast. Salle 1013 Adresse Sophie Germain