# Mathematics Colloquia and Seminars

### P-partitions revisited

Algebra & Discrete Mathematics

 Speaker: Victor Reiner, University of Minnesota Location: 1147 MSB Start time: Fri, Jan 7 2011, 2:10PM

(joint work with Valentin Feray) Counting the linear extensions of a general partially ordered set (poset) is hard. We'll explain a new product formula which works for a certain class of posets, generalizing a formula for forest posets due to Knuth, and its q-generalization by Bjorner and Wachs. We'll also explain how this formula arises naturally when one re-examines Stanley's P-partitions from the perspective of convex cones and their affine semigroup rings.