数学理论与应用 ›› 2022, Vol. 42 ›› Issue (3): 61-.doi: 10.3969/j.issn.1006-8074.2022.03.005

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树的指数型反遗忘指数的极值问题

曾明瑶 1,2, 邓汉元 2,∗
  

  1. 1. 怀化学院数学与计算科学学院, 怀化, 418000;
    2. 湖南师范大学数学与统计学院, 长沙, 410081
  • 出版日期:2022-09-30 发布日期:2022-09-28
  • 通讯作者: 邓汉元 (1965­), 教授, 博士, 从事图论, 组合数学研究; E−mail: hydeng@hunnan.edu.cn
  • 基金资助:
    国家自然科学基金 (11971164), 湖南省自然科学基金 (2020JJ4423) 资助

The Extremal Value of Exponential Inverse Forgotten Index of a Tree

Zeng Mingyao1,2 ,Deng Hanyuan2,∗
  

  1. 1. School of Mathematics and Computation Science, Huaihua University, Huaihua 418000, China;
    2. School of Mathematics and Statistics, Hunan Normal University, Changsha 410081, China
  • Online:2022-09-30 Published:2022-09-28

摘要: 设~$G$ 为简单图, $E(G)$为其边集, 则~$G$ 的指数型反遗忘指数~$e^{\frac{1}{\mathcal{F}}}(G)=\sum_{uv\in E(G)}e^{\left(\frac{1}{{d_G^2(u)}}+\frac{1}{{d_G^2t(v)}}\right)}$, 其中~$d_G(u)$ 为~$G$ 中顶点~$u$ 的度. 本文首先给出树的指数型反遗忘指数~$e^{\frac{1}{\mathcal{F}}}$ 的极小值和对应的极图, 然后研究当~$e^{\frac{1}{\mathcal{F}}}$ 达到极大值时对应的极图的一些结构性质.

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Abstract:

For a simple graph $G$ with edge set $E(G)$, the exponential inverse forgotten index of $G$ is defined as ~$e^{\frac{1}{\mathcal{F}}}(G)=\sum_{uv\in E(G)}e^{\left(\frac{1}{{d_G^2(u)}}+\frac{1}{{d_G^2(v)}}\right)}$, where $d_G(u)$ is the degree of the vertex $u$ in $G$. In this paper, firstly, we give the minimum value of exponential inverse forgotten index of a tree and determine its corresponding extremal graph. Then, we investigate the maximum value of the exponential inverse forgotten index and describe the structural characteristics of the extremal graph. 


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