A new proof of an Eğecioğlu--Remmel inverse Kostka matrix problem via a Garsia--Milne involution involving Sym and NSym
Edward E. Allen, Kyle Celano, Sarah K. Mason
TL;DR
The paper develops a full combinatorial proof of the reverse Kostka identity $K^{-1}K=I$ by first establishing NSym analogues $\tilde{K}\tilde{K}^{-1}=I$ and $\tilde{K}^{-1}\tilde{K}=I$ via sign-reversing involutions on pairs of immaculate tableaux and tunnel hook coverings. A NSym–Sym reduction then recovers the classical Kostka identities in $\mathrm{Sym}$, while a Garsia–Milne involution framework provides a unified, bijective approach to the Jacobi–Trudi–type structure for immaculate functions. The authors also connect their constructions to special rim hook tableaux, establishing a bijection with tunnel hook coverings and highlighting a distinct bijection from Loehr–Mendes to a permutation model. Overall, the work presents a general, involution-based paradigm that translates signed combinatorial sums into concrete identities and suggests broader applicability to related symmetric-function problems and Jacobi–Trudi formulas.
Abstract
Eğecioğlu and Remmel provide a combinatorial proof (using special rim hook tableaux) that the product of the Kostka matrix $K$ and its inverse $K^{-1}$ equals the identity matrix $I$. They then pose the problem of proving the reverse identity $K^{-1}K =I$ combinatorially. Sagan and Lee prove a special case of this identity using overlapping special rim hook tableaux. Loehr and Mendes provide a full proof using bijective matrix algebra that relies on the Eğecioğlu--Remmel map. In this article, we solve the problem in full generality independent of the Eğecioğlu--Remmel bijection. To do this, we start by proving NSym versions of both Kostka matrix identities using sign-reversing involutions involving the tunnel hook coverings recently introduced by the first and third authors. Then we modify our sign-reversing involutions to reduce to Sym. Finally, we show that our bijection is different than the Loehr and Mendes result by constructing an injective map between special rim tableaux and the symmetric group $S_n.$
