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arXiv · 2501.02726

Connectivity and matching extendability of optimal $1$-embedded graphs on the torus

Shohei Koizumi·Yusuke Suzuki
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Abstract

In this paper, we discuss optimal $1$-toroidal graphs (abbreviated as O1TG), which are drawn on the torus so that every edge crosses another edge at most once, and has $n$ vertices and exactly $4n$ edges. We first consider connectivity of O1TGs, and give the characterization of O1TGs having connectivity exactly $k$ for each $k\in \{4, 5, 6, 8\}$. In our argument, we also show that there exists no O1TG having connectivity exactly $7$. Furthermore, using the result above, we discuss extendability of matchings, and give the characterization of $1$-, $2$- and $3$-extendable O1TGs in turn.

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Shohei Koizumi, Yusuke Suzuki. 2025-01-06. Connectivity and matching extendability of optimal $1$-embedded graphs on the torus. https://arxiv.org/abs/2501.02726

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