Extremal graphs for the sum of the two largest signless Laplacian eigenvalues

Carla Silva Oliveira, Leonardo de Lima, Paula Rama +1

Let G be a simple graph on $n$ vertices and $e(G)$ edges. Consider $Q(G)=D+A$ as the signless Laplacian of $G$, where $A$ is the adjacency matrix and $D$ is the diagonal matrix…