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arXiv 2312.03384math.CO
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具有大围长的次三次平面图的支配

Domination of subcubic planar graphs with large girth

Eun-Kyung Cho, Eric Culver, Stephen G. Hartke, Vesna Iršič

AI总结:

本文研究大围长次三次平面图的支配数,按顶点度数加权,分别证明围长至少 8 和 9 时的两个新严格上界。

摘要:

自 Reed 于 1996 年猜想阶为 $n$ 的连通三次图的支配数至多为 $\lceil \frac13 n \rceil$ 以来,三次图的支配数得到了广泛研究。现在已知该猜想在一般情况下是错误的,但 Henning 和 Dorbec 证明了它对围长至少为 9 的图成立。Zhu 和 Wu 对 2-连通三次平面图提出了类似猜想。本文中,我们给出次三次平面图支配数的一个新上界:若 $G$ 是围长至少为 8 的次三次平面图,则 $γ(G) < n_0 + \frac{3}{4} n_1 + \frac{11}{20} n_2 + \frac{7}{20} n_3$,其中对 $i \in \{0,1,2,3\}$,$n_i$ 表示 $G$ 中度数为 $i$ 的顶点数。我们还证明,若 $G$ 是围长至少为 9 的次三次平面图,则 $\gamma(G) < n_0 + \frac{13}{17} n_1 + \frac{9}{17} n_2 + \frac{6}{17} n_3$。

英文摘要:

Since Reed conjectured in 1996 that the domination number of a connected cubic graph of order $n$ is at most $\lceil \frac13 n \rceil$, the domination number of cubic graphs has been extensively studied. It is now known that the conjecture is false in general, but Henning and Dorbec showed that it holds for graphs with girth at least $9$. Zhu and Wu stated an analogous conjecture for 2-connected cubic planar graphs. In this paper, we present a new upper bound for the domination number of subcubic planar graphs: if $G$ is a subcubic planar graph with girth at least 8, then $γ(G) < n_0 + \frac{3}{4} n_1 + \frac{11}{20} n_2 + \frac{7}{20} n_3$, where $n_i$ denotes the number of vertices in $G$ of degree $i$, for $i \in \{0,1,2,3\}$. We also prove that if $G$ is a subcubic planar graph with girth at least 9, then $γ(G) < n_0 + \frac{13}{17} n_1 + \frac{9}{17} n_2 + \frac{6}{17} n_3$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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