New bounds of degree-based topological indices for some classes of c-cyclic graphs

Making use of a majorization technique for a suitable class of graphs, we derive upper and lower bounds for some topological indices depending on the degree sequence over all vertices, namely the first general Zagreb index and the first multiplicative Zagreb index. Specifically, after characterizing c-cyclic graphs (0 ≤ c ≤ 6) as those whose degree sequence belongs to particular subsets of Rn, we identify the maximal and minimal vectors of these subsets with respect to the majorization order. This technique allows us to determine lower and upper bounds of the above indices recovering some existing results in the literature as well as obtaining new ones.