Turán problem for ${\mathcal{K}}_4^{-}$-free signed graphs

Fan Chen, Xiying Yuan

Suppose that $\dot{G}$ is an unbalanced signed graph of order $n$ with $e(\dot{G})$ edges. Let $\rho (\dot{G})$ be the spectral radius of $\dot{G}$, and ${\mathcal{K}}_4^{-}$ be the set of…