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Related papers: Equivariant Kazhdan--Lusztig Polynomials of Thagom…

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In this paper, we focus on the equivariant inverse Kazhdan--Lusztig polynomials of thagomizer matroids, a natural family of graphic matroids associated with the complete tripartite graphs $K_{1,1,n}$. These polynomials were introduced by…

Combinatorics · Mathematics 2025-10-14 Alice L. L. Gao , Yun Li , Matthew H. Y. Xie

Motivated by the concepts of the inverse Kazhdan-Lusztig polynomial and the equivariant Kazhdan-Lusztig polynomial, Proudfoot defined the equivariant inverse Kazhdan-Lusztig polynomial for a matroid. In this paper, we show that the…

Combinatorics · Mathematics 2021-05-19 Alice L. L. Gao , Matthew H. Y. Xie , Arthur L. B. Yang

In analogy with the classical Kazhdan-Lusztig polynomials for Coxeter groups, Elias, Proudfoot and Wakefield introduced the concept of Kazhdan-Lusztig polynomials for matroids. It is known that both the classical Kazhdan-Lusztig polynomials…

Combinatorics · Mathematics 2021-08-16 Alice L. L. Gao , Matthew H. Y. Xie

The equivariant Kazhdan-Lusztig polynomial of a matroid was introduced by Gedeon, Proudfoot, and Young. Gedeon conjectured an explicit formula for the equivariant Kazhdan-Lusztig polynomials of thagomizer matroids with an action of…

Combinatorics · Mathematics 2019-02-05 Matthew H. Y. Xie , Philip B. Zhang

We define the equivariant Kazhdan-Lusztig polynomial of a matroid equipped with a group of symmetries, generalizing the nonequivariant case. We compute this invariant for arbitrary uniform matroids and for braid matroids of small rank.

Combinatorics · Mathematics 2016-11-23 Katie Gedeon , Nicholas Proudfoot , Ben Young

We study the way in which equivariant Kazhdan-Lusztig polynomials, equivariant inverse Kazhdan-Lusztig polynomials, and equivariant Z-polynomials of matroids change under the operation of relaxation of a collection of stressed hyperplanes.…

Combinatorics · Mathematics 2022-02-15 Trevor Karn , George Nasr , Nicholas Proudfoot , Lorenzo Vecchi

We present a formula which relates the Kazhdan-Lusztig polynomial of a matroid $M$, as defined by Elias, Proudfoot and Wakefield, to the Kazhdan--Lusztig polynomials of the matroid obtained by deleting an element, and various contractions…

Combinatorics · Mathematics 2023-06-13 Tom Braden , Artem Vysogorets

Inspired by the notion of equivariant log-concavity, we introduce the concept of induced log-concavity for a sequence of representations of a finite group. For an equivariant matroid equipped with a symmetric group action or a finite…

Combinatorics · Mathematics 2023-07-21 Alice L. L. Gao , Ethan Y. H. Li , Matthew H. Y. Xie , Arthur L. B. Yang , Zhong-Xue Zhang

We introduce $q$-analogues of uniform matroids, which we call $q$-niform matroids. While uniform matroids admit actions of symmetric groups, $q$-niform matroids admit actions of finite general linear groups. We show that the equivariant…

Combinatorics · Mathematics 2018-09-05 Nicholas Proudfoot

The inverse Kazhdan--Lusztig polynomial of a matroid was introduced by Gao and Xie, and the inverse $Z$-polynomial of a matroid was introduced by Ferroni, Matherne, Stevens, and Vecchi. In this paper, we study these two polynomials for fan…

Combinatorics · Mathematics 2026-05-13 Alice L. L. Gao , Ya-Xing Li , Yun Li

We provide a combinatorial interpretation of the Kazhdan--Lusztig polynomial of the matroid arising from the braid arrangement of type $\mathrm{A}_{n-1}$, which gives an interpretation of the intersection cohomology Betti numbers of the…

Combinatorics · Mathematics 2024-01-31 Luis Ferroni , Matt Larson

Gao and Xie (2021) conjectured that the inverse Kazhdan-Lusztig polynomial of any matroid is log-concave. Although the inverse Kazhdan-Lusztig polynomial may not always have only real roots, we conjecture that the Hadamard product of an…

Combinatorics · Mathematics 2025-04-25 Matthew H. Y. Xie , Philip B. Zhang

We give a concrete combinatorial interpretation of the coefficients of the Kazhdan-Lusztig polynomials of Dowling geometries, a family of matroids which generalizes braid matroids of types A and B. Furthermore, we interpret the coefficients…

Combinatorics · Mathematics 2026-05-06 Luis Ferroni , Matt Larson

We study equivariant Kazhdan--Lusztig (KL) and $Z$-polynomials of matroids. We formulate an equivariant generalization of a result by Braden and Vysogorets that relates the equivariant KL and $Z$-polynomials of a matroid with those of a…

Combinatorics · Mathematics 2025-04-25 Luis Ferroni , Jacob P. Matherne , Lorenzo Vecchi

Motivated by the notion of the inverse $Z$-polynomial introduced by Ferroni, Matherne, Stevens, and Vecchi, we study the equivariant inverse $Z$-polynomial of a matroid equipped with a finite group. We prove that the coefficients of the…

Combinatorics · Mathematics 2026-01-27 Alice L. L. Gao , Yun Li , Matthew H. Y. Xie

The Kazhdan-Lusztig polynomial of a matroid was introduced by Elias, Proudfoot and Wakefield, whose properties need to be further explored. In this paper we prove that the Kazhdan-Lusztig polynomials of fan matroids coincide with Motzkin…

Combinatorics · Mathematics 2018-02-13 Linyuan Lu , Matthew H. Y. Xie , Arthur L. B. Yang

In this article we make several contributions of independent interest. First, we introduce the notion of stressed hyperplane of a matroid, essentially a type of cyclic flat that permits to transition from a given matroid into another with…

Combinatorics · Mathematics 2022-11-16 Luis Ferroni , George D. Nasr , Lorenzo Vecchi

The Kazhdan-Lusztig polynomial of a matroid was introduced by Elias, Proudfoot, and Wakefield [{\it Adv. Math. 2016}]. Let $U_{m,d}$ denote the uniform matroid of rank $d$ on a set of $m+d$ elements. Gedeon, Proudfoot, and Young [{\it J.…

Combinatorics · Mathematics 2018-06-29 Alice L. L. Gao , Linyuan Lu , Matthew H. Y. Xie , Arthur L. B. Yang , Philip B. Zhang

We introduce thagomizer matroids and compute the Kazhdan-Lusztig polynomial of a rank $n+1$ thagomizer matroid by showing that the coefficient of $t^k$ is equal to the number of Dyck paths of semilength $n$ with $k$ long ascents. We also…

Combinatorics · Mathematics 2017-10-04 Katie R. Gedeon

The equivariant Kazhdan-Lusztig polynomial of a braid matroid may be interpreted as the intersection cohomology of a certain partial compactification of the configuration space of n distinct labeled points in the plane, regarded as a graded…

Representation Theory · Mathematics 2019-07-25 Nicholas Proudfoot , Ben Young
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