Sombor index of clean graphs

Abstract

Let $G = (V, E)$ be a graph with the vertex set $V (G)$ and edge set $E(G)$. The Sombor index of $G$, $SO(G)$, is defined as $\sum_{uv\in E(G)} \sqrt{deg(u)^2 + deg(v)^2}$, where $deg(u)$ is the degree of vertex $u$ in $V (G)$. The clean graph of a ring R, denoted by $Cl(R)$, is a graph with vertex set $\{(e, u) : e \in Id(R), u \in U(R)\}$ and two distinct vertices $(e, u)$ and$(f, v)$ are adjacent if and only if $ef = 0$ or $uv = 1$ ($Id(R)$ and $U(R)$ are the sets of idempotents and unit elements of R, respectively). The induced subgraph on $\{(e, u) : e \in Id^{*}(R), u \in U(R)\}$ is denoted by $Cl_2(R)$. In this paper, $SO(Cl2(\mathbb{Z}_n))$, for different values of the positive integer $n$, is investigated.