University of Minnesota Combinatorics Seminar
Tuesday, August 23, 2011
12:20pm in 364 Vincent Hall



Minkowski decompositions of associahedra

Carsten Lange

Freie Universitat - Berlin


Abstract

The associahedron is a polytope whose vertex-edge-graph is isomorphic to the flip graph of an associated convex polygon and there are many interesting ways to obtain realisations. I focus on realisations that are generalised permutahedra obtained by Hohlweg and Lange. As shown by Ardila, Benedetti and Doker, generalised permutahedra have a Minkowski decomposition into faces of a standard simplex and Möbius inversion relates the right-hand sides of inequalities to the coefficients of this decomposition.

I will review the construction of Hohlweg and Lange, show that the general formula of Ardila, Benedetti and Doker can be significantly simplified for these instances and give a combinatorial interpretation of the Minkowski coefficients in terms of certain path lengths of the associated polygon.