Eigenvalue multiplicity in cubic graphs

Citation

Rowlinson P (2014) Eigenvalue multiplicity in cubic graphs. Linear Algebra and Its Applications, 444, pp. 211-218. https://doi.org/10.1016/j.laa.2013.11.036

Abstract
Let G be a connected cubic graph of order n with μ as an eigenvalue of multiplicity k. We show that (i) if μ∉{-1,0} then k≤12n, with equality if and only if μ=1 and G is the Petersen graph; (ii) if μ=-1 then k≤12n+1, with equality if and only if G=K4; (iii) if μ= then k≤12n+1, with equality if and only if G=2K3¯.

Keywords
Cubic graph; Eigenvalue; Star complement

Journal
Linear Algebra and Its Applications: Volume 444