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arXiv 2409.01285math.CO
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某些直积图丛环上环与笛卡尔图丛环上环的最优 $L(d,1)$-标号

Optimal $L(d,1)$-labeling of certain direct graph bundles cycles over cycles and Cartesian graph bundles cycles over cycles

Irena Hrastnik Ladinek

AI总结:

本文研究环上环构成的直积图丛与笛卡尔图丛的 $L(d,1)$-标号问题,证明其最优标号数满足 $λ^d_1(X)\leq 2d+2$,并在 $1\leq d\leq 4$ 时达到等号。

摘要:

图 $G$ 的 $L(d,1)$-标号是将非负整数分配给顶点,使得相邻顶点所获标号至少相差 $d$,距离为二的顶点所获标号至少相差 $1$,其中 $d\geq 1$。令 $λ^d_1 (G)$ 表示使 $G$ 存在使用 $\{0,1,\ldots , λ\}$ 中标号的 $L(d,1)$-标号的最小 $λ$。我们证明,对于某些直积图丛 $X= C_m\times^{σ_\ell} C_n$ 和某些笛卡尔图丛 $X= C_m\Box^{σ_\ell} C_n$,其中 $σ_\ell$ 是循环 $\ell$-移位,有 $λ^d_1(X)\leq 2d+2$,并且当 $1\leq d\leq 4$ 时等号成立。

英文摘要:

An $L(d,1)$-labeling of a graph $G$ is an assignment of nonnegative integers to the vertices such that adjacent vertices receive labels that differ by at least $d$ and those at a distance of two receive labels that differ by at least one, where $d\geq 1$. Let $λ^d_1 (G)$ denote the least $λ$ such that $G$ admits an $L(d,1)$-labeling using labels from $\{0,1,\ldots , λ\}$. We prove that $λ^d_1(X)\leq 2d+2$ for certain direct graph bundle $X= C_m\times^{σ_\ell} C_n$ and certain Cartesian graph bundle $X= C_m\Box^{σ_\ell} C_n$, where $σ_\ell$ is a cyclic $\ell$-shift, with equality if $1\leq d\leq 4$.

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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