The Sombor index and coindex of two-trees

Zenan Du, Lihua You, Hechao Liu +1

The Sombor index of a graph $G$, introduced by Ivan Gutman, is defined as the sum of the weights $\sqrt{d_G(u{)}^2+d_G(v{)}^2}$ of all edges $uv$ of $G$, where $d_G(u)$ denotes the deg…