Mathematics Department Colloquium: Chip firing, root systems, permutohedra, and Coxeter arrangements.

Colloquium | October 26 | 4-5 p.m. | 60 Evans Hall

 Alex Postnikov, MIT

 Department of Mathematics

The abelian sandpile model (also known as the chip firing game) is a simple dynamical system with surprisingly rich and nontrivial structure. We discuss a version of this game for root systems, which has even more mysterious structure than the classical chip firing. This study is closely linked with combinatorics of convex (and nonconvex) polytopes, such as permutohedra, and affine Coxeter arrangements.

Joint work with Pavel Galashin, Sam Hopkins, and Thomas McConville.