运筹学学报 ›› 2023, Vol. 27 ›› Issue (3): 150-158.doi: 10.15960/j.cnki.issn.1007-6093.2023.03.012

•   • 上一篇    下一篇

不含偶圈(n, m)-图匹配多项式的最大根

袁玲1, 王文环1,*()   

  1. 1. 上海大学数学系, 上海 200444
  • 收稿日期:2019-12-19 出版日期:2023-09-15 发布日期:2023-09-14
  • 通讯作者: 王文环 E-mail:whwang@shu.edu.cn
  • 作者简介:王文环, E-mail: whwang@shu.edu.cn
  • 基金资助:
    国家自然科学基金(11001166)

On the largest root of the matching polynomials of (n, m)-graphs without even cycles

Ling YUAN1, Wenhuan WANG1,*()   

  1. 1. Department of Mathematics, Shanghai University, Shanghai 200444, China
  • Received:2019-12-19 Online:2023-09-15 Published:2023-09-14
  • Contact: Wenhuan WANG E-mail:whwang@shu.edu.cn

摘要:

令图$G$ 是具有$n$个顶点的简单连通图。图$G$ 的匹配多项式定义为$\sum_{k=0}^{[n/2]}(-1)^k$ $m(G, k)x^{n-2k}$, 其中$m(G, k)$ 是图$G$$k$-匹配的数目, $0\leq k\leq [n/2]$。令$\Phi_{n, m}$ 是具有$n$ 个顶点和$m$ 条边的不含偶圈图的集合, 其中$n\leq m\leq \frac{3(n-1)}{2}$。本文介绍了四个新的比较匹配多项式最大根的变换方法, 从而刻画了$\Phi_{n, m}$ 中具有匹配多项式最大根的图。

关键词: 匹配多项式, 最大根, (n, m)-图, 偶圈

Abstract:

Let $G$ be a simple connected graph with $n$ vertices. The matching polynomial of $G$ is given by $\sum_{k=0}^{[n/2]}(-1)^km(G, k)x^{n-2k}$, where $m(G, k)$ is the number of $k$-matchings in $G$ with $0\leq k\leq [n/2]$. Let $\Phi_{n, m}$ be the set of graphs with $n$ vertices and $m$ edges having no even cycles, where $n\leq m\leq \frac{3(n-1)}{2}$. In this paper, four new transformations for comparing the largest roots of matching polynomials are introduced and the graph with the largest root of matching polynomial is characterized among graphs in $\Phi_{n, m}$.

Key words: matching polynomial, the largest root, (n, m)-graph, even cycles

中图分类号: