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More on graphs with just three distinct eigenvalues

Rowlinson P (2017) More on graphs with just three distinct eigenvalues, Applicable Analysis and Discrete Mathematics, 11, pp. 74-80.

Let G be a connected non-regular non-bipartite graph whose adjacency matrix has spectrum ρ, µ(k) , λ(l) , where k, l ∈ IN and ρ > µ > λ. We show that if µ is non-main then δ(G) ≥ 1 + µ − λµ, with equality if and only if G is of one of three types, derived from a strongly regular graph, a symmetric design or a quasi-symmetric design (with appropriate parameters in each case).

AuthorsRowlinson Peter
Publication date2017
Date accepted by journal11/11/2016
PublisherUniversity of Belgrade
ISSN 1452-8630

Applicable Analysis and Discrete Mathematics: Volume 11 (2016)

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