Abstract :
Recently, a novel topological index, Sombor index, was introduced by Gutman, defined as
SO(G) = ∑uv∈E(G) jdu + dv ,
2 2
where du denotes the degree of vertex u . In this paper, we first
determine the maximum Sombor index among cacti with n vertices
and t cycles, then determine the maximum Sombor index among
cacti with perfect matchings. We also characterize corresponding
maximum cacti.
