Distinguished filtrations of the $0$-Hecke modules for dual immaculate quasisymmetric functions
Abstract
Let range over the set of compositions. Dual immaculate quasisymmetric functions , introduced by Berg, Bergeron, Saliola, Serrano, and Zabrocki, provide a quasisymmetric analogue of Schur functions. They also constructed an indecomposable -Hecke module whose image under the quasisymmetric characteristic is . In this paper, we prove that admits a distinguished filtration with respect to the basis of Young quasisymmetric Schur functions. This result offers a novel representation-theoretic interpretation of the positive expansion of in the basis of Young quasisymmetric Schur functions. A key tool in our proof is Mason's analogue of the Robinson-Schensted-Knuth algorithm, for which we establish a version of Green's theorem. As an unexpected byproduct of our investigation, we construct an indecomposable -Hecke module whose image under the quasisymmetric characteristic is the Young quasisymmetric Schur function . Further properties of this module are also investigated. And, by applying a suitable automorphism twist to this module, we obtain an indecomposable -Hecke module whose image under the quasisymmetric characteristic is the quasisymmetric Schur function .
Keywords
Cite
@article{arxiv.2501.11304,
title = {Distinguished filtrations of the $0$-Hecke modules for dual immaculate quasisymmetric functions},
author = {So-Yeon Lee and Young-Tak Oh},
journal= {arXiv preprint arXiv:2501.11304},
year = {2025}
}
Comments
50 pages