Inverse Kazhdan-Lusztig polynomials of matroids under deletion

Fuente: arXiv
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Main Authors: Braden, Tom, Ferroni, Luis, Matherne, Jacob P., Nepal, Nutan
Format: Preprint
Published: 2025
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author Braden, Tom
Ferroni, Luis
Matherne, Jacob P.
Nepal, Nutan
author_facet Braden, Tom
Ferroni, Luis
Matherne, Jacob P.
Nepal, Nutan
contents We provide a deletion formula for the inverse Kazhdan--Lusztig polynomial and the inverse $Z$-polynomial of a matroid. Our formulas provide analogues to the deletion formulas of Braden--Vysogorets for Kazhdan--Lusztig and $Z$-polynomials. We discuss several consequences, which include closed formulas and recursions for these invariants on uniform matroids, projective geometries, glued cycles, and arbitrary matroids of corank $2$. As a relevant application of our deletion formula, we show the existence of a matroid of rank $19$ which disproves a conjecture of Xie and Zhang concerning a real-rootedness property of inverse Kazhdan--Lusztig polynomials.
format Preprint
id arxiv_https___arxiv_org_abs_2510_01086
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Inverse Kazhdan-Lusztig polynomials of matroids under deletion
Braden, Tom
Ferroni, Luis
Matherne, Jacob P.
Nepal, Nutan
Combinatorics
We provide a deletion formula for the inverse Kazhdan--Lusztig polynomial and the inverse $Z$-polynomial of a matroid. Our formulas provide analogues to the deletion formulas of Braden--Vysogorets for Kazhdan--Lusztig and $Z$-polynomials. We discuss several consequences, which include closed formulas and recursions for these invariants on uniform matroids, projective geometries, glued cycles, and arbitrary matroids of corank $2$. As a relevant application of our deletion formula, we show the existence of a matroid of rank $19$ which disproves a conjecture of Xie and Zhang concerning a real-rootedness property of inverse Kazhdan--Lusztig polynomials.
title Inverse Kazhdan-Lusztig polynomials of matroids under deletion
topic Combinatorics
url https://arxiv.org/abs/2510.01086