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 Γm, the set of hexagonal systems with m edges. The main idea consists in constructing hexagonal systems with maximal number of inlets in Γm which have simultaneously minimal number of hexagons. Also we show that the convex spiral Sh has extremal TI   -value over Γ3h+⌈12h−3⌉.