The largest eigenvalue of ${\mathcal{C}}_4^{-}$-free signed graphs

Yongang Wang, Huiqiu Lin

Let ${\mathcal{C}}_k^{-}$ be the set of all negative $C_k$. For odd cycle, Wang, Hou and Li [29] gave a spectral condition for the existence of negative $C_3$ in unbalanced signed…