The multiplicity of a Hermitian eigenvalue on graphs

Qian-Qian Chen, Ji-Ming Guo, Zhiwen Wang

For a graph $G$, let $\mathcal{S}(G)$ be the set consisting of Hermitian matrices whose graph is $G$. Denoted by $m_B(G,\lambda )$ the multiplicity of an eigenvalue $\lambda$ of $B(G)\in \mathc…