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Autores principales: Chen, Yanru, Fu, Houshan, Li, Ang, Wang, Suijie
Formato: Preprint
Publicado: 2026
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Acceso en línea:https://arxiv.org/abs/2606.00599
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author Chen, Yanru
Fu, Houshan
Li, Ang
Wang, Suijie
author_facet Chen, Yanru
Fu, Houshan
Li, Ang
Wang, Suijie
contents We establish a convolution formula for the characteristic polynomial of a finite geometric semilattice $M$: \[ χ(M,st)=\sum_{X\in \underline{M}} s^{r-{\rm rk}_{\underline{M}}(X)}χ(\underline{M}^X,t)\,χ(M_{(X)},s), \] where $\underline{M}$ denotes the centralization of $M$, and $M_{(X)}$ denotes the localization at $X$. This generalizes a nice formula of Southerland, Southern, and Zhou, which is recovered at $s=1$. When specialized to hyperplane arrangements, the identity yields a new expansion closely related to Wang's convolution formula. We further provide a combinatorial interpretation of the convolution formula using the finite field method over $\mathbb{F}_{p^2}$ and $\mathbb{F}_p$.
format Preprint
id arxiv_https___arxiv_org_abs_2606_00599
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Convolution-type Identity for Characteristic Polynomials of Geometric Semilattices
Chen, Yanru
Fu, Houshan
Li, Ang
Wang, Suijie
Combinatorics
We establish a convolution formula for the characteristic polynomial of a finite geometric semilattice $M$: \[ χ(M,st)=\sum_{X\in \underline{M}} s^{r-{\rm rk}_{\underline{M}}(X)}χ(\underline{M}^X,t)\,χ(M_{(X)},s), \] where $\underline{M}$ denotes the centralization of $M$, and $M_{(X)}$ denotes the localization at $X$. This generalizes a nice formula of Southerland, Southern, and Zhou, which is recovered at $s=1$. When specialized to hyperplane arrangements, the identity yields a new expansion closely related to Wang's convolution formula. We further provide a combinatorial interpretation of the convolution formula using the finite field method over $\mathbb{F}_{p^2}$ and $\mathbb{F}_p$.
title Convolution-type Identity for Characteristic Polynomials of Geometric Semilattices
topic Combinatorics
url https://arxiv.org/abs/2606.00599