Hilbert polynomials of configuration spaces over graphs of circumference at most 1

Fuente: arXiv
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Main Authors: An, Byung Hee, Kim, Jang Soo
Format: Preprint
Published: 2025
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author An, Byung Hee
Kim, Jang Soo
author_facet An, Byung Hee
Kim, Jang Soo
contents The $ k $-configuration space $ B_kΓ$ of a topological space $ Γ$ is the space of sets of $ k $ distinct points in $ Γ$. In this paper, we consider the case where $ Γ$ is a graph of circumference at most $1$. We show that for all $ k\ge0 $, the $ i $-th Betti number of $ B_kΓ$ is given by a polynomial $P_Γ^i(k)$ in $ k $, called the Hilbert polynomial of $ Γ$. We find an expression for the Hilbert polynomial $P_Γ^i(k)$ in terms of those coming from the canonical $1$-bridge decomposition of $ Γ$. We also give a combinatorial description of the coefficients of $P_Γ^i(k)$.
format Preprint
id arxiv_https___arxiv_org_abs_2505_24416
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hilbert polynomials of configuration spaces over graphs of circumference at most 1
An, Byung Hee
Kim, Jang Soo
Geometric Topology
Algebraic Topology
Combinatorics
Primary: 20F36, 55R80, Secondary: 05C10, 13E15
The $ k $-configuration space $ B_kΓ$ of a topological space $ Γ$ is the space of sets of $ k $ distinct points in $ Γ$. In this paper, we consider the case where $ Γ$ is a graph of circumference at most $1$. We show that for all $ k\ge0 $, the $ i $-th Betti number of $ B_kΓ$ is given by a polynomial $P_Γ^i(k)$ in $ k $, called the Hilbert polynomial of $ Γ$. We find an expression for the Hilbert polynomial $P_Γ^i(k)$ in terms of those coming from the canonical $1$-bridge decomposition of $ Γ$. We also give a combinatorial description of the coefficients of $P_Γ^i(k)$.
title Hilbert polynomials of configuration spaces over graphs of circumference at most 1
topic Geometric Topology
Algebraic Topology
Combinatorics
Primary: 20F36, 55R80, Secondary: 05C10, 13E15
url https://arxiv.org/abs/2505.24416