Strong ${\mathfrak{sl}}_2$ Actions and Symmetric Chain Decompositions

Abstract

We introduce a notion of a strong ${\mathfrak{sl}}_2$-action on a poset, and conjecture the existence of such an action is equivalent to the existence of a symmetric chain decomposition of that poset. We explain the intuition behind the conjecture, go through a number of explicit examples, and prove some special cases and relaxations of the conjecture. Then we explain a computational experiment where we tested the conjecture on millions of randomly constructed rank-symmetric, rank-unimodal, and strongly Sperner posets.

arXiv comment36 pages, many figures