Bubble sort and Howe duality for staircase matrices

Fuente: arXiv
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Autori principali: Khoroshkin, Anton, Makedonskyi, Ievgen
Natura: Preprint
Pubblicazione: 2025
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author Khoroshkin, Anton
Makedonskyi, Ievgen
author_facet Khoroshkin, Anton
Makedonskyi, Ievgen
contents In this paper, we present an independent proof of the Cauchy identities for staircase matrices, originally discovered in arXiv:2411.03117, using the combinatorics of the Bruhat poset and the bubble-sort procedure. Additionally, we derive new insights into certain coefficients appearing in one of these identities. The first part of the paper focuses on combinatorial aspects. It is self-contained, of independent interest, and introduces a generalization of parabolic Bruhat graphs for monotone functions on an arborescent poset. The second part examines the intersections of Demazure modules within a given integrable representation. Finally, we propose a generalization of the classical Howe duality for staircase matrices in terms of the corresponding distributive lattice of Demazure submodules. Computing the associated character yields the desired Cauchy identities for staircase matrices.
format Preprint
id arxiv_https___arxiv_org_abs_2502_21184
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Bubble sort and Howe duality for staircase matrices
Khoroshkin, Anton
Makedonskyi, Ievgen
Representation Theory
Combinatorics
17B10, 33C52, 06A11
In this paper, we present an independent proof of the Cauchy identities for staircase matrices, originally discovered in arXiv:2411.03117, using the combinatorics of the Bruhat poset and the bubble-sort procedure. Additionally, we derive new insights into certain coefficients appearing in one of these identities. The first part of the paper focuses on combinatorial aspects. It is self-contained, of independent interest, and introduces a generalization of parabolic Bruhat graphs for monotone functions on an arborescent poset. The second part examines the intersections of Demazure modules within a given integrable representation. Finally, we propose a generalization of the classical Howe duality for staircase matrices in terms of the corresponding distributive lattice of Demazure submodules. Computing the associated character yields the desired Cauchy identities for staircase matrices.
title Bubble sort and Howe duality for staircase matrices
topic Representation Theory
Combinatorics
17B10, 33C52, 06A11
url https://arxiv.org/abs/2502.21184