On the maximum atom-bond sum-connectivity index of graphs

The atom-bond sum-connectivity (ABS) index of a graph G with edges e(1),...,m(1 )is the sum of the numbers root 1-2(d(ei)+ 2)(-1 )over 1 <= i <= m, wheredeiis the number of edges adjacent to e(i). In this article, westudy the maximum values of the ABS index over graphs with given parameters. More specifically, wedetermine the maximum ABS index of connected graphs of a given order with afixed (i) minimum degree,(ii) maximum degree, (iii) chromatic number, (iv) independence number, or (v) number of pendent vertices.We also characterize the graphs attaining the maximum ABS values in all of these classes.