**Date & Time:** Friday, March 20, 2015, 15:30-16:30.

**Venue:** Ramanujan Hall

**Title:** Tamari lattice and its extensions

**Speaker:** Xavier G. Viennot, University of Bordeaux

**Abstract:** The vertices of the Tamari lattice are binary trees with an order relation defined by a rotation on binary trees. Such a lattice can be realized geometrically as a convex polyhedron, called the associahedron.
I will begin with a survey of this active subject and then will give some
extensions of the Tamari lattice in relation with the so-called rational
Catalan combinatorics and higher diagonal coinvariants (joint work with L.-F. PrĂ©ville-Ratelle).