The harmonic index of a graph G is defined as the sum of the weights 2/d(u)+d(v) of all edges uv of G, where d(u) denotes the degree of a vertex u in G. In this paper, we present the minimum harmonic index for unicyclic graphs with given diameter and characterize the corresponding extremal graphs. This answers an unsolved problem of Zhu and Chang [26]. Keywords: harmonic index, unicyclic graphs, diameter.
机构:
S China Agr Univ, Coll Sci, Dept Appl Math, Guangzhou 510640, Peoples R ChinaS China Normal Univ, Dept Math, Guangzhou 510631, Guangdong, Peoples R China
Li, Feng
Zhou, Bo
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机构:
S China Normal Univ, Dept Math, Guangzhou 510631, Guangdong, Peoples R ChinaS China Normal Univ, Dept Math, Guangzhou 510631, Guangdong, Peoples R China