Deterministic approximate counting of colorings with fewer than $2Δ$ colors via absence of zeros

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Hauptverfasser: Bencs, Ferenc, Berrekkal, Khallil, Regts, Guus
Format: Preprint
Veröffentlicht: 2024
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author Bencs, Ferenc
Berrekkal, Khallil
Regts, Guus
author_facet Bencs, Ferenc
Berrekkal, Khallil
Regts, Guus
contents Let $Δ,q\geq 3$ be integers. We prove that there exists $η\geq 0.002$ such that if $q\geq (2-η)Δ$, then there exists an open set $\mathcal{U}\subset \mathbb{C}$ that contains the interval $[0,1]$ such that for each $w\in \mathcal{U}$ and any graph $G=(V,E)$ of maximum degree at most $Δ$, the partition function of the anti-ferromagnetic $q$-state Potts model evaluated at $w$ does not vanish. This provides a (modest) improvement on a result of Liu, Sinclair, and Srivastava, and breaks the $q=2Δ$-barrier for this problem. As a direct consequence we obtain via Barvinok's interpolation method a deterministic polynomial time algorithm to approximate the number of proper $q$-colorings of graphs of maximum degree at most $Δ$, provided $q\geq (2-η)Δ$.
format Preprint
id arxiv_https___arxiv_org_abs_2408_04727
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Deterministic approximate counting of colorings with fewer than $2Δ$ colors via absence of zeros
Bencs, Ferenc
Berrekkal, Khallil
Regts, Guus
Combinatorics
Discrete Mathematics
Data Structures and Algorithms
Let $Δ,q\geq 3$ be integers. We prove that there exists $η\geq 0.002$ such that if $q\geq (2-η)Δ$, then there exists an open set $\mathcal{U}\subset \mathbb{C}$ that contains the interval $[0,1]$ such that for each $w\in \mathcal{U}$ and any graph $G=(V,E)$ of maximum degree at most $Δ$, the partition function of the anti-ferromagnetic $q$-state Potts model evaluated at $w$ does not vanish. This provides a (modest) improvement on a result of Liu, Sinclair, and Srivastava, and breaks the $q=2Δ$-barrier for this problem. As a direct consequence we obtain via Barvinok's interpolation method a deterministic polynomial time algorithm to approximate the number of proper $q$-colorings of graphs of maximum degree at most $Δ$, provided $q\geq (2-η)Δ$.
title Deterministic approximate counting of colorings with fewer than $2Δ$ colors via absence of zeros
topic Combinatorics
Discrete Mathematics
Data Structures and Algorithms
url https://arxiv.org/abs/2408.04727