The Harmonic Indices of Polyomino Chains
 作者： Hanyuan Deng,  S. Balachandran,  S. K. Ayyaswamy,  Y. B. Venkatakrishnan 作者单位： 1College of Mathematics and Computer Science, Hunan Normal University2Department of Mathematics, School of Humanities and Sciences SASTRA University 刊名： National Academy Science Letters, 2014, Vol.37 (5), pp.451-455 来源数据库： Springer Nature Journal DOI： 10.1007/s40009-014-0249-0 关键词： Harmonic index;  Polyomino chain;  Extremal graph; 英文摘要： Abstract(#br)The harmonic index $$H\left( G\right)$$ H G of a graph $$G$$ G is defined as the sum of the weights $$\frac{2}{d_{u}+ d_{v}}$$ 2 d u + d v of all edges $$uv$$ u v in $$G$$ G , where $$d_{u}$$ d u denotes the degree of a vertex $$u$$ u in $$G$$ G . In this paper, the harmonic indices of polyomino chains are computed. Also, the extremal polyomino chains with respect to harmonic index are determined.