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arXiv · 2609.39538

On the chromatic number of pseudohemisphere hypergraphs

Balázs István Szabó
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Abstract

A pseudohemisphere hypergraph is a hypergraph $\mathcal{H}$ with an ordered set of vertices $V$ for which there exists an $ABA$-free hypergraph $\mathcal{F}$ on $V$ and a subset $X$ of $V$ such that the hyperedge set of $\mathcal{H}$ is a subset of $\{FΔX: F\in \mathcal{F}\cup \overline{\mathcal{F}}\}$. We prove that the chromatic number of pseudohemisphere hypergraphs is at most four.

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Balázs István Szabó. 2026-09-30. On the chromatic number of pseudohemisphere hypergraphs. https://arxiv.org/abs/2609.39538

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