Extremal graphs with respect to variable sum exdeg index via majorization

The variable sum exdeg index of a graph G is defined as SEIa(G)=∑uv∈E(G)[adegG(u)+adegG(v)], where a ≠ 1 is a positive real number. The aim of this paper is applying the majorization technique to obtain the maximum and minimum values of variable sum exdeg index of trees, unicyclic, bicyclic and tricyclic graphs.