Vertex-degree-based topological indices of hexagonal systems with equal number of edges
In this paper, we find extremal values of vertex-degree-based topological indices over m, the set of hexagonal systems with m edges. The main idea consists in constructing hexagonal systems with maximal number of inlets in m which have simultaneously minimal number of hexagons. Also we show that the convex spiral Sh has extremal TI -value over 3h+12h3.