Richardson tableaux and noncrossing partial matchings

TL;DR

This paper establishes a novel correspondence between Richardson tableaux, noncrossing partial matchings, and Motzkin paths, revealing new properties and connecting to $q$-Catalan numbers.

Contribution

It demonstrates that insertion tableaux of noncrossing partial matchings are exactly Richardson tableaux, creating a bijection with Motzkin paths and linking to $q$-Catalan numbers.

Findings

Set of insertion tableaux of noncrossing partial matchings equals Richardson tableaux

Established a bijection between Richardson tableaux and Motzkin paths

Connected $q$-counting of Richardson tableaux to $q$-Catalan numbers

Abstract

Richardson tableaux are a remarkable subfamily of standard Young tableaux introduced by Karp and Precup in order to index the irreducible components of Springer fibers equal to Richardson varieties. We show that the set of insertion tableaux of noncrossing partial matchings on $\{1,2,,\ldots, n\}$ by applying the Robinson--Schensted algorithm coincides with the set of Richardson tableaux of size $n$. This leads to a natural one-to-one correspondence between the set of Richardson tableaux of size $n$ and the set of Motzkin paths with $n$ steps, in response to a problem proposed by Karp and Precup. As consequences, we recover some known and establish new properties for Richardson tableaux. Especially, we relate the $q$-counting of Richardson tableaux to $q$-Catalan numbers.