A short bijective proof of dimension identities of Erickson and Hunziker

Abstract

In a recent paper (arXiv:2301.09744), Erickson and Hunziker consider partitions in which the arm-leg difference is an arbitrary constant $m$. In previous works, these partitions are called $(-m)$-asymmetric partitions. Regarding these partitions and their conjugates as the highest weights, they prove an identity yielding an infinite family of dimension equalities between $\mathfrak{gl}_n$ and $\mathfrak{gl}_{n+m}$ modules. Their proof proceeds by the manipulations of the hook content formula. We give a simple bijective proof of their result.