The Vertex PI and Szeged Indices of Chain Graphs
نویسندگان
چکیده
The vertex Padmakar-Ivan (PIv) index of a graph G was introduced as the sum over all edges e = uv of G of the number of vertices which are not equidistant to the vertices u and v. In this paper we provide an analogue to the results of T. Mansour and M. Schork [The PI index of bridge and chain graphs, MATCH Commun. Math. Comput. Chem. 61 (2009) 723-734]. Two efficient formulas for calculating the vertex PI index and Szeged index of chain graphs are determined. Using these formulas, the vertex PI index and Szeged index of a spiro chain of hexagons are computed.
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