Coxeter and Schubert combinatorics of $μ$-Involutions

Fuente: arXiv
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Main Authors: Chou, Jack Chen-An, Hamaker, Zachary
Format: Preprint
Published: 2026
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author Chou, Jack Chen-An
Hamaker, Zachary
author_facet Chou, Jack Chen-An
Hamaker, Zachary
contents The variety of complete quadrics is the wonderful compactification of $GL_n/O_n$ and admits a cell decomposition into Borel orbits indexed by combinatorial objects called $μ$-involutions. We study Coxeter-theoretic properties of $μ$-involutions with results including a combinatorial description for their atoms, an exchange lemma, and transposition-like operators that characterize their Bruhat order. The corresponding orbit closures can be realized inside the flag variety. In this setting, we study the cohomology representatives of these orbits, which are, up to a scalar, the $μ$-involution Schubert polynomials. We expand $μ$-involution Schubert polynomials as a multiplicity-free sum of $ν$-involution Schubert polynomials when $ν$ refines $μ$ and provide recurrences analogous to Monk's rule for Schubert polynomials.
format Preprint
id arxiv_https___arxiv_org_abs_2604_03379
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Coxeter and Schubert combinatorics of $μ$-Involutions
Chou, Jack Chen-An
Hamaker, Zachary
Combinatorics
05E14, 14N15
The variety of complete quadrics is the wonderful compactification of $GL_n/O_n$ and admits a cell decomposition into Borel orbits indexed by combinatorial objects called $μ$-involutions. We study Coxeter-theoretic properties of $μ$-involutions with results including a combinatorial description for their atoms, an exchange lemma, and transposition-like operators that characterize their Bruhat order. The corresponding orbit closures can be realized inside the flag variety. In this setting, we study the cohomology representatives of these orbits, which are, up to a scalar, the $μ$-involution Schubert polynomials. We expand $μ$-involution Schubert polynomials as a multiplicity-free sum of $ν$-involution Schubert polynomials when $ν$ refines $μ$ and provide recurrences analogous to Monk's rule for Schubert polynomials.
title Coxeter and Schubert combinatorics of $μ$-Involutions
topic Combinatorics
05E14, 14N15
url https://arxiv.org/abs/2604.03379