Merging the A-and Q-spectral theories

Let G be a graph with adjacency matrix A(G), and let D(G) be the diagonal matrix of the degrees of G: The signless Laplacian Q(G) of G is defined as Q(G):= A(G) +D(G). Cvetkovic called the study of the adjacency matrix the A-spectral theory, and the study of the signless Laplacian{the Q-spectral the...

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Bibliographic Details
Published inApplicable analysis and discrete mathematics Vol. 11; no. 1; pp. 81 - 107
Main Author Nikiforov, V.
Format Journal Article
LanguageEnglish
Published 01.04.2017
Online AccessGet full text
ISSN1452-8630
2406-100X
2406-100X
DOI10.2298/AADM1701081N

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Summary:Let G be a graph with adjacency matrix A(G), and let D(G) be the diagonal matrix of the degrees of G: The signless Laplacian Q(G) of G is defined as Q(G):= A(G) +D(G). Cvetkovic called the study of the adjacency matrix the A-spectral theory, and the study of the signless Laplacian{the Q-spectral theory. To track the gradual change of A(G) into Q(G), in this paper it is suggested to study the convex linear combinations A_ (G) of A(G) and D(G) defined by A? (G) := ?D(G) + (1 - ?)A(G), 0 ? ? ? 1. This study sheds new light on A(G) and Q(G), and yields, in particular, a novel spectral Tur?n theorem. A number of open problems are discussed. nema
ISSN:1452-8630
2406-100X
2406-100X
DOI:10.2298/AADM1701081N