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SOME RESULTS ON THE DIFFERENCE OF THE ZAGREB INDICES OF A GRAPH
Published online by Cambridge University Press: 02 June 2015
Abstract
The classical first and second Zagreb indices of a graph $G$ are defined as $M_{1}(G)=\sum _{v\in V(G)}d(v)^{2}$ and $M_{2}(G)=\sum _{e=uv\in E(G)}d(u)d(v),$ where $d(v)$ is the degree of the vertex $v$ of $G.$ Recently, Furtula et al. [‘On difference of Zagreb indices’, Discrete Appl. Math.178 (2014), 83–88] studied the difference of $M_{1}$ and $M_{2},$ and showed that this difference is closely related to the vertex-degree-based invariant $RM_{2}(G)=\sum _{e=uv\in E(G)}[d(u)-1][d(v)-1]$, the reduced second Zagreb index. In this paper, we present sharp bounds for the reduced second Zagreb index, given the matching number, independence number and vertex connectivity, and we also completely determine the extremal graphs.
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- Research Article
- Information
- Bulletin of the Australian Mathematical Society , Volume 92 , Issue 2 , October 2015 , pp. 177 - 186
- Copyright
- © 2015 Australian Mathematical Publishing Association Inc.
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