Citation Bell FK & Rowlinson P (2003) On the multiplicities of graph eigenvalues. Bulletin of the London Mathematical Society, 35 (3), pp. 401-408. https://doi.org/10.1112/S0024609303002030
Abstract Star complements and associated quadratic functions are used to obtain a sharp upper bound for the order of a graph with an eigenspace of prescribed codimension. It is shown that for regular graphs the bound can be reduced by 1, and that this reduced bound is attained by a regular graph G if and only if G is an extremal strongly regular graph. 2000 Mathematics Subject Classification 05C50.
Journal Bulletin of the London Mathematical Society: Volume 35, Issue 3
Bell, Francis K; Rowlinson, Peter
Oxford University Press for London Mathematical Society