Journée-séminaire de combinatoire

(équipe CALIN du LIPN, université Paris-Nord, Villetaneuse)

Le 24 septembre 2013 à 14h00-15h00 en B107, Bérénice Oger nous parlera de : Action of the symmetric groups on the homology of the hypertree posets

Résumé : The set of hypertrees on n vertices can be endowed with a poset structure. This poset has been used by McCammond and Meier to study the group of motions of the trivial link, which is an analogue of the braid group. They also proved that this poset is Cohen-Macaulay and computed the dimension of its only homology group. After a short introduction on this topological context, we explain how we used the theory of species to compute the action of the symmetric group on this homology group. We then link it with the PreLie operad.

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