论文标题
相对于受限加权邻接矩阵光谱半径的极端树木
Extremal trees with respect to spectral radius of restrictedly weighted adjacency matrices
论文作者
论文摘要
对于图$ g =(v,e)$和$ v_ {i} \在v $中,用$ d_ {i} $表示顶点$ v_ {i} $的程度。令$ f(x,y)> 0 $为$ x $和$ y $中的真正对称功能。图$ g $的加权邻接矩阵$ a_ {f}(g)$是一个方形矩阵,其中$(i,j)$ - 条目等于$ \ displayStyStyle f(d_ {i},d_ {j {j})$,如果Vertices $ v_ {i} $ v_ {i} $ and $ v_ jott and; Li和Wang \ cite {u9}试图统一方法来研究由各种拓扑指数加权的图形加权邻接矩阵的光谱半径。如果$ \ displayStyle f'_ {x}(x,y)\ geq0 $和$ \ displayStyle f''_ {x}(x,x,y)\ geq0 $,则据说在可变$ x $中分别增加了$ \ displayStyle f(x,y)$。他们获得了$ a_ {f}(g)$的最大光谱半径的树是一颗星或双星,当$ f(x,y)$增加并以可变$ x $的形式凸出。在本文中,我们添加以下限制:$ f(x_ {1},y_ {1})\ geq f(x_ {2},y_ {2})$如果$ x_ {1}+y_ {1}+y_ {1} = x_ {2} = x_ {2}+y_ {2}+y_ {2} $ nid x_ mid x__________________________________________________________________________________________________________________________- x_ {2} -y_ {2} \ mid $ 并致电$ a_f(g)$ $ g $的受限加权邻接矩阵。受限加权的邻接矩阵包含由First Zagreb索引加权的加权邻接矩阵,第一个超Zagreb索引,一般总和连接性索引,被遗忘的索引,somber索引,$ p $ -sombor索引等等。我们获得了$ a_ {f}(g)$的最小和最大光谱半径的极端树。我们的结果推动了Li和Wang对统一方法的研究。
For a graph $G=(V,E)$ and $v_{i}\in V$, denote by $d_{i}$ the degree of vertex $v_{i}$. Let $f(x, y)>0$ be a real symmetric function in $x$ and $y$. The weighted adjacency matrix $A_{f}(G)$ of a graph $G$ is a square matrix, where the $(i,j)$-entry is equal to $\displaystyle f(d_{i}, d_{j})$ if the vertices $v_{i}$ and $v_{j}$ are adjacent and 0 otherwise. Li and Wang \cite{U9} tried to unify methods to study spectral radius of weighted adjacency matrices of graphs weighted by various topological indices. If $\displaystyle f'_{x}(x, y)\geq0$ and $\displaystyle f''_{x}(x, y)\geq0$, then $\displaystyle f(x, y)$ is said to be increasing and convex in variable $x$, respectively. They obtained the tree with the largest spectral radius of $A_{f}(G)$ is a star or a double star when $f(x, y)$ is increasing and convex in variable $x$. In this paper, we add the following restriction: $f(x_{1},y_{1})\geq f(x_{2},y_{2})$ if $x_{1}+y_{1}=x_{2}+y_{2}$ and $\mid x_{1}-y_{1}\mid>\mid x_{2}-y_{2}\mid$ and call $A_f(G)$ the restrictedly weighted adjacency matrix of $G$. The restrictedly weighted adjacency matrix contains weighted adjacency matrices weighted by first Zagreb index, first hyper-Zagreb index, general sum-connectivity index, forgotten index, Somber index, $p$-Sombor index and so on. We obtain the extremal trees with the smallest and the largest spectral radius of $A_{f}(G)$. Our results push ahead Li and Wang's research on unified approaches.