The chromaticity of a family of 6-bridge graph

For such a graph G, suppose P(G, lambda) denote the chromatic polynomial of graph G. Let G and H are two graphs, then G and H are said to be chromatically equivalent (or simply chi-equivalent) denoted by G similar to H, if P(G, lambda) = P(H, lambda). A graph G is said to be chromatically unique (or simply chi-unique) if for any graph H such that G similar to H, we have G congruent to H, that is G is isomorphic to H. In this paper, the chromaticity of a family of 6-bridge graph, that is theta(a,a,b,b,c,c) aabbcc. is investigated. The result is presented in Theorem 3.1 in Section 3 of this paper.