Building polytopes from posets

10/06/2015 - 12:15pm
10/06/2015 - 1:10pm
Satyan Devadoss (Williams College and HMC)

The “associahedron”, the famous polytope birthed in the 1950s and 1960s, is a geometric realization of the poset of bracketings on n letters. Indeed, its vertices correspond to all different ways these letters can be multiplied, enumerated by the Catalan numbers. There exists a natural generalization of this object: Given any graph G, we can construct a convex polytope based on the connectivity properties of G. This polytope, called the "graph associahedra”, appears in numerous areas including tropical geometry, algebraic geometry, biological statistics, and Floer homology. For this talk, we broaden the notion of connectivity on graphs to connectivity on posets. This naturally extends associativity notions to a far larger class of objects, including cell complexes. The entire talk is infused with visual imagery and concrete examples.

Millikan 2099, Pomona College