Distinguishing number and distinguishing index of natural and fractional powers of graphs
نویسندگان
چکیده مقاله:
The distinguishing number (resp. index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (resp. edge labeling) with $d$ labels that is preserved only by a trivial automorphism. For any $n in mathbb{N}$, the $n$-subdivision of $G$ is a simple graph $G^{frac{1}{n}}$ which is constructed by replacing each edge of $G$ with a path of length $n$. The $m^{th}$ power of $G$, is a graph with same set of vertices of $G$ and an edge between two vertices if and only if there is a path of length at most $m$ between them in $G$. The fractional power of $G$, is the $m^{th}$ power of the $n$-subdivision of $G$, i.e., $(G^{frac{1}{n}})^m$ or $n$-subdivision of $m$-th power of $G$, i.e., $(G^m)^{frac{1}{n}}$. In this paper we study the distinguishing number and the distinguishing index of the natural and the fractional powers of $G$. We show that the natural powers more than one of a graph are distinguished by at most three edge labels. We also show that for a connected graph $G$ of order $n geqslant 3$ with maximum degree $Delta (G)$, and for $kgeqslant 2$, $D(G^{frac{1}{k}})leqslant lceil sqrt[k]{Delta (G)} rceil$. Finally we prove that for $mgeqslant 2$, the fractional power of $G$, i.e., $(G^{frac{1}{k}})^m$ and $(G^m)^{frac{1}{k}}$ are distinguished by at most three edge labels.
منابع مشابه
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عنوان ژورنال
دوره 43 شماره 7
صفحات 2471- 2482
تاریخ انتشار 2017-12-01
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