数学理论与应用 ›› 2021, Vol. 41 ›› Issue (1): 33-.

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图的强和与强积导出的距离整谱图

卢俊颖    刘伟俊     鲁卢*   

  1. School of Mathematics and Statistics, Central South University, Changsha 410083,China
  • 出版日期:2021-03-30 发布日期:2021-08-10

Distance Integral Graphs Generated by Strong Sum and Strong Product

中南大学数学与统计学院,长沙,410083   

  • Online:2021-03-30 Published:2021-08-10
  • Contact: Lu Lu;E−mail:lulugdmath@163.com
  • Supported by:
    This work is supported by NSFC (Nos. 12001544, 11671402, 11871479)

摘要: 对于两个连通图 $G$和$H$,它们的强和$G\oplus H$是一个点集为$V(G)\times V(H)$,边集为 $\{(u,v)(u',v')\mid uu'\in E(G),v=v'\}\cup\{(u,v)(u',v')\mid uu'\in E(G),vv'\in E(H)\}$的图;它们的强积 $G\otimes H$是一个点集为$V(G)\times V(H)$,边集为$\{(u,v)(u',v')\mid uu'\in E(G),v=v'\}\cup\{(u,v)(u',v')\mid uu'\in E(G),vv'\in E(H)\}\cup\{(u,v)(u',v')\mid u=u',vv'\in E(H)\}$的图.当 $H$的直径小于3时,本文完全确定了$G\oplus H$和 $G\otimes H$中的距离.进而,当$G$ 和 $H$满足某些条件时,我们得到了$G\oplus H$和 $G\otimes H$的距离谱.作为应用,我们得到了一些由强和与强积导出的距离谱图.特别的,我们得到了一个新的由强积导出的距离整谱图无穷类.

关键词: 距离谱 ,  距离整谱图 ,  强和 ,  强积

Abstract: For two connected graphs $G$ and $H$, the strong sum $G\oplus H$ is the graph with vertex set $V(G)\times V(H)$ and edge set $\{(u,v)(u',v')\mid uu'\in E(G),v=v'\}\cup\{(u,v)(u',v')\mid uu'\in E(G),vv'\in E(H)\}$, and the strong product $G\otimes H$ is the graph with vertex set $V(G)\times V(H)$ and edge set $\{(u,v)(u',v')\mid uu'\in E(G),v=v'\}\cup\{(u,v)(u',v')\mid uu'\in E(G),vv'\in E(H)\}\cup\{(u,v)(u',v')\mid u=u',vv'\in E(H)\}$. In this paper we completely obtain the distances in the $G\oplus H$ and $G\otimes H$ when $H$ has diameter less than $3$. Furthermore, we get the distance spectra of $G\oplus H$ and $G\otimes H$ when $G$ and $H$ satisfy some conditions. As applications, some distance integral graphs generated by strong sum and strong product are obtained. Especially, we get a new infinite class of distance integral graphs generated by strong product.

Key words: Distance spectrum ,  Distance integral graph ,  , Strong sum ,  , Strong product