Extremal Laplacian energy of $\overrightarrow{C_{k+1}}$-free digraphs

Xiuwen Yang, Lin-Peng Zhang

The Laplacian energy of a digraph $G$ is defined as ${\sum }_{i=1}^n{\lambda }_i^2$, where ${\lambda }_i$ are the eigenvalues of the Laplacian matrix of $G$. A (di)graph $G$ is said to be $H$-free if…