Furtula, BorisGutman, IvanEdiz, Suleyman2025-05-102025-05-1020140166-218X1872-677110.1016/j.dam.2014.06.0112-s2.0-84907711924https://doi.org/10.1016/j.dam.2014.06.011https://hdl.handle.net/20.500.14720/15537Gutman, Ivan/0000-0001-9681-1550; Ediz, Suleyman/0000-0003-0625-3634; Furtula, Boris/0000-0002-5056-6892The classical first and second Zagreb indices of a graph G are defined as M-1 = Sigma(v) d(v)(2) and M-2 = Sigma(uv) d(u) d(v), where d(v) is the degree of the vertex v of G. So far, the difference of M-1 and M-2 has not been studied. We show that this difference is closely related to the vertex-degree-based invariant RM2 = Sigma(uv) (d(u) - 1) (d(v) - 1), and determine a few basic properties of RM2. (C) 2014 Elsevier B.V. All rights reserved.eninfo:eu-repo/semantics/openAccessDegree (Of Vertex)Zagreb IndexFirst Zagreb IndexSecond Zagreb IndexArticle178Q3Q28388WOS:000343343200008