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arXiv · 2410.23225

Deterministic counting from coupling independence

Xiaoyu Chen·Weiming Feng·Heng Guo·Xinyuan Zhang·Zongrui Zou
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Abstract

We show that spin systems with bounded degrees and coupling independence admit fully polynomial time approximation schemes (FPTAS). We design a new recursive deterministic counting algorithm to achieve this. As applications, we give the first FPTASes for $q$-colourings on graphs of bounded maximum degree $\Delta\ge 3$, when $q\ge (11/6-\varepsilon_0)\Delta$ for some small $\varepsilon_0\approx 10^{-5}$, or when $\Delta\ge 125$ and $q\ge 1.809\Delta$, and on graphs with sufficiently large (but constant) girth, when $q\geq\Delta+3$. These bounds match the current best randomised approximate counting algorithms by Chen, Delcourt, Moitra, Perarnau, and Postle (2019), Carlson and Vigoda (2024), and Chen, Liu, Mani, and Moitra (2023), respectively.

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Xiaoyu Chen, Weiming Feng, Heng Guo, Xinyuan Zhang, Zongrui Zou. 2024-10-30. Deterministic counting from coupling independence. https://arxiv.org/abs/2410.23225

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