The general connectivity indices of catacondensed hexagonal systems

The general connectivity index R-alpha(G) of a graph G is defined as Sigma((uv))(d(u)d(v))(alpha), where uv is an edge of G, alpha is an element of R and alpha not equal 0. In this paper, a formula is given for computing the general connectivity indices R-alpha of catacondensed hexagonal systems. We show that the general connectivity index R-alpha is monotone decreasing over the number of inlets in the system. The catacondensed hexagonal systems with the first up to the third extremal general connectivity indices are completely characterized.