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arXiv 2401.16615math.CO
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图的全约束数研究

On Total Bondage Number of Graphs

E. G. K. M. Gamlath, Bing Wei

AI总结:

该研究围绕图的全约束数展开,基于图的最大度推导其通用上界,针对平面图、连通平面图及树等特定图类优化上界结果,完善相关引理,丰富了图论中全约束数的理论研究。

摘要:

本文探讨了无孤立顶点的有限图中的全约束(total bondage)概念。若顶点集$D$满足图$G$中的每个顶点$v$都在$D$中有一个邻点,则称$D$为全控制集。$G$中所有全控制集的最小基数记为$γ_t(G)$。全约束边集$B$是$G$的边的子集,满足从$G$中移除$B$后不会产生孤立顶点,且所得图$G-B$的全控制数严格大于$γ_t(G)$。$G$的全约束数记为$b_t(G)$,定义为此类全约束边集的最小基数。本文基于图的最大度建立了$b_t(G)$的上界。值得注意的是,对于最小度$δ(G) \neq 3$的平面图,我们证明了$b_t(G) \neq Δ+ 8$或$b_t(G) \neq 10$。此外,对于满足$δ(G) \neq 3$且围长$g(G) \neq 4$的连通平面图,我们证明若$G$不包含度和不超过7的边,则$b_t(G) \neq Δ+ 3$。我们还改进了树的全约束数的部分上界,完善了现有引理,并得出了特定图类的全约束数上界。

英文摘要:

In this paper, we explore the concept of total bondage in finite graphs without isolated vertices. A vertex set $D$ is considered a total dominating set if every vertex $v$ in the graph $G$ has a neighbor in $D$. The minimum cardinality of all total dominating sets in $G$ is denoted as $γ_t(G)$. A total bondage edge set $B$ is a subset of the edges of $G$ such that the removal of $B$ from $G$ does not create isolated vertices, and the total dominating number of the resulting graph $G-B$ is strictly greater than $γ_t(G)$. The total bondage number of $G$, denoted $b_t(G)$, is defined as the minimum cardinality of such total bondage edge sets. Our paper establishes upper bounds on $b_t(G)$ based on the maximum degree of a graph. Notably, for planar graphs with minimum degree $δ(G) \geq 3$, we prove $b_t(G) \leq Δ+ 8$ or $b_t(G) \leq 10$. Additionally, for a connected planar graph with $δ(G) \geq 3$ and $g(G) \geq 4$, we show that $b_t(G) \leq Δ+ 3$ if $G$ does not contain an edge with degree sum at most 7. We also improve some upper bounds of the total bondage number for trees, enhance existing lemmas, and find upper bounds for total bondage in specific graph classes.

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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