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On spectral spread of generalized distance matrix of a graph

Combinatorics 2019-07-23 v1

Abstract

For a simple connected graph GG, let D(G)D(G), Tr(G)Tr(G), DL(G)D^{L}(G) and DQ(G)D^{Q}(G), respectively be the distance matrix, the diagonal matrix of the vertex transmissions, distance Laplacian matrix and the distance signless Laplacian matrix of a graph GG. The convex linear combinations Dα(G)D_{\alpha}(G) of Tr(G)Tr(G) and D(G)D(G) is defined as Dα(G)=αTr(G)+(1α)D(G)D_{\alpha}(G)=\alpha Tr(G)+(1-\alpha)D(G), 0α10\leq \alpha\leq 1. As D0(G)=D(G),   2D12(G)=DQ(G),   D1(G)=Tr(G)D_{0}(G)=D(G), ~~~ 2D_{\frac{1}{2}}(G)=D^{Q}(G), ~~~ D_{1}(G)=Tr(G) and Dα(G)Dβ(G)=(αβ)DL(G)D_{\alpha}(G)-D_{\beta}(G)=(\alpha-\beta)D^{L}(G), this matrix reduces to merging the distance spectral, distance Laplacian spectral and distance signless Laplacian spectral theories. Let 1(G)2(G)n(G)\partial_{1}(G)\geq \partial_{2}(G)\geq \dots \geq \partial_{n}(G) be the eigenvalues of Dα(G)D_{\alpha}(G) and let DαS(G)=1(G)n(G)D_{\alpha}S(G)=\partial_{1}(G)-\partial_{n}(G) be the generalized distance spectral spread of the graph GG. In this paper, we obtain some bounds for the generalized distance spectral spread Dα(G)D_{\alpha}(G). We also obtain relation between the generalized distance spectral spread Dα(G)D_{\alpha}(G) and the distance spectral spread SD(G)S_{D}(G). Further, we obtain the lower bounds for DαS(G)D_{\alpha}S(G) of bipartite graphs involving different graph parameters and we characterize the extremal graphs for some cases. We also obtain lower bounds for DαS(G)D_{\alpha}S(G) in terms of clique number and independence number of the graph GG and characterize the extremal graphs for some cases.

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Cite

@article{arxiv.1907.09462,
  title  = {On spectral spread of generalized distance matrix of a graph},
  author = {Hilal A. Ganie and S. Pirzada and A. Alhevaz and M. Baghipur},
  journal= {arXiv preprint arXiv:1907.09462},
  year   = {2019}
}

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17 pages