Characteristic quasi-polynomials of deletions of Shi arrangements of type B and their period collapse

Fuente: arXiv
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Main Authors: Higashitani, Akihiro, Nakashima, Norihiro
Format: Preprint
Published: 2024
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author Higashitani, Akihiro
Nakashima, Norihiro
author_facet Higashitani, Akihiro
Nakashima, Norihiro
contents Characteristic quasi-polynomials are the enumerative functions counting the number of elements in the complement of hyperplane arrangements modulo positive integers. A notable phenomenon in this context is period collapse, where the quasi-polynomial reduces to a polynomial or has a smaller period than the lcm period. In this paper, we compute the characteristic quasi-polynomials of the restriction of the Shi arrangement of type B by one given hyperplane. As a corollary, we completely determine whether period collapse occurs in the characteristic quasi-polynomial of the deletion of the Shi arrangement of type B. This implies the solution for the conjecture posed by Higashitani, Tran and Yoshinaga in this case.
format Preprint
id arxiv_https___arxiv_org_abs_2405_20102
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Characteristic quasi-polynomials of deletions of Shi arrangements of type B and their period collapse
Higashitani, Akihiro
Nakashima, Norihiro
Combinatorics
32S22 (Primary), 52C35 (Secondary)
Characteristic quasi-polynomials are the enumerative functions counting the number of elements in the complement of hyperplane arrangements modulo positive integers. A notable phenomenon in this context is period collapse, where the quasi-polynomial reduces to a polynomial or has a smaller period than the lcm period. In this paper, we compute the characteristic quasi-polynomials of the restriction of the Shi arrangement of type B by one given hyperplane. As a corollary, we completely determine whether period collapse occurs in the characteristic quasi-polynomial of the deletion of the Shi arrangement of type B. This implies the solution for the conjecture posed by Higashitani, Tran and Yoshinaga in this case.
title Characteristic quasi-polynomials of deletions of Shi arrangements of type B and their period collapse
topic Combinatorics
32S22 (Primary), 52C35 (Secondary)
url https://arxiv.org/abs/2405.20102