Mercredi 25 Mai
Heure: 
14:00  15:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
On the reconstruction of trees from their Upolynomial. 
Description: 
José AlistePrieto The Upolynomial of a graph was introduced by Noble and Welsh as a generalization of some invariants coming from Knot theory. It also generalizes the chromatic symmetric function of Stanley. In this talk, we will consider the problem of whether there exist nonisomorphic trees with the same Upolynomial (or,equivalently, with the same chromatic symmetric function).
We will survey what is know about the Upolynomial and this problem. In particular, we will show how to recover some classic invariants from the Upolynomial and we exhibit several subclasses of trees for which a solution of this problem is known. FInally, we construct some nonisomorphic trees with "almost" the same Upolynomial, based on solutions of an old problem in Number theory due to ProuhetTarryEscott. 

