On the independent set polynomial of graphs and claw-free graphs

Fuente: arXiv
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Main Authors: Fialho, Paula M. S., Procacci, Aldo
Format: Preprint
Published: 2025
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author Fialho, Paula M. S.
Procacci, Aldo
author_facet Fialho, Paula M. S.
Procacci, Aldo
contents We present two new contributions to the study of the independence polynomial $Z_G(z)$ of a finite simple graph $G = (V,E)$. First, we provide an improved lower bound for the zero-free region of $Z_G(z)$ for the important class of claw-free graphs. Our bound exceeds the classical Shearer radius and it is derived through a refined application of the Fernández-Procacci criterion using properties of the local neighborhood structure in claw-free graphs. Second, we establish a novel combinatorial expression for $Z_G(z)$, inspired by the connection with the abstract polymer gas models in statistical mechanics, which offers a new structural interpretation of the polynomial and may be of independent interest. These results strengthen the connection between statistical physics, combinatorics, and graph theory, and suggest new approaches for analytic exploration.
format Preprint
id arxiv_https___arxiv_org_abs_2505_22766
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the independent set polynomial of graphs and claw-free graphs
Fialho, Paula M. S.
Procacci, Aldo
Combinatorics
Mathematical Physics
05C31
We present two new contributions to the study of the independence polynomial $Z_G(z)$ of a finite simple graph $G = (V,E)$. First, we provide an improved lower bound for the zero-free region of $Z_G(z)$ for the important class of claw-free graphs. Our bound exceeds the classical Shearer radius and it is derived through a refined application of the Fernández-Procacci criterion using properties of the local neighborhood structure in claw-free graphs. Second, we establish a novel combinatorial expression for $Z_G(z)$, inspired by the connection with the abstract polymer gas models in statistical mechanics, which offers a new structural interpretation of the polynomial and may be of independent interest. These results strengthen the connection between statistical physics, combinatorics, and graph theory, and suggest new approaches for analytic exploration.
title On the independent set polynomial of graphs and claw-free graphs
topic Combinatorics
Mathematical Physics
05C31
url https://arxiv.org/abs/2505.22766