<p>Kemeny’s constant of a simple connected graph <i>G</i> is the average travel time for a random walk to reach a randomly target vertex selected according to the stationary distribution, which is an important parameter reflecting the structural properties of <i>G</i>. A <i>cactus</i> is a connected graph in which every block is either a single edge or a cycle. In this paper, we address the problem of determining the graph that maximizes (or minimize) the Kemeny’s constant among all cacti. We identify the extremal cacti that attain the maximum and the minimum values of Kemeny’s constants among all cacti of order <i>n</i> with <i>t</i> cycles, respectively.</p>

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Cacti with Extremal Kemeny’s Constants

  • Yirong Zheng,
  • Longjian Liao,
  • Jianxi Li

摘要

Kemeny’s constant of a simple connected graph G is the average travel time for a random walk to reach a randomly target vertex selected according to the stationary distribution, which is an important parameter reflecting the structural properties of G. A cactus is a connected graph in which every block is either a single edge or a cycle. In this paper, we address the problem of determining the graph that maximizes (or minimize) the Kemeny’s constant among all cacti. We identify the extremal cacti that attain the maximum and the minimum values of Kemeny’s constants among all cacti of order n with t cycles, respectively.