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Main Authors: Liu, Yongqiang, Yoshinaga, Masahiko
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2503.23976
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author Liu, Yongqiang
Yoshinaga, Masahiko
author_facet Liu, Yongqiang
Yoshinaga, Masahiko
contents Let $\mathcal{L}$ be a rank one local system with field coefficient on the complement $M(\mathcal{A})$ of an essential complex hyperplane arrangement $\mathcal{A}$ in $\mathbb{C}^\ell$. Dimca-Papadima and Randell independently showed that $M(\mathcal{A})$ is homotopy equivalent to a minimal CW-complex. It implies that $\dim H^k(M(\mathcal{A}),\mathcal{L}) \leq b_k(M(\mathcal{A}))$. In this paper, we show that if $\mathcal{A}$ is real, then the inequality holds as equality for some $0\leq k\leq \ell$ if and only if $\mathcal{L}$ is the constant sheaf. The proof is using the descriptions of local system cohomology of $M(\mathcal{A})$ in terms of chambers.
format Preprint
id arxiv_https___arxiv_org_abs_2503_23976
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Maximal Betti number for local system cohomology of hyperplane arrangement complements
Liu, Yongqiang
Yoshinaga, Masahiko
Algebraic Geometry
Let $\mathcal{L}$ be a rank one local system with field coefficient on the complement $M(\mathcal{A})$ of an essential complex hyperplane arrangement $\mathcal{A}$ in $\mathbb{C}^\ell$. Dimca-Papadima and Randell independently showed that $M(\mathcal{A})$ is homotopy equivalent to a minimal CW-complex. It implies that $\dim H^k(M(\mathcal{A}),\mathcal{L}) \leq b_k(M(\mathcal{A}))$. In this paper, we show that if $\mathcal{A}$ is real, then the inequality holds as equality for some $0\leq k\leq \ell$ if and only if $\mathcal{L}$ is the constant sheaf. The proof is using the descriptions of local system cohomology of $M(\mathcal{A})$ in terms of chambers.
title Maximal Betti number for local system cohomology of hyperplane arrangement complements
topic Algebraic Geometry
url https://arxiv.org/abs/2503.23976