Convex caterpillars are Schur-Positive

Abstract

A remarkable result of Stanley shows that the set of maximal chains in the non-crossing partition lattice of type $A$ is Schur-positive, where descents are defined by a distinguished edge labeling. A bijection between these chains and labeled trees was presented by Goulden and Yong. Using Adin-Roichman's variant of Bj\"orner's $EL$-labeling, we show that the subset of maximal chains in the non-crossing partition lattice of type $A$, whose underlying tree is a convex caterpillar, is Schur-positive.