Convex combination of first and second eigenvalues of trees

Hitesh Kumar, Bojan Mohar, Shivaramakrishna Pragada +1

For a graph $G$, let ${\lambda }_1(G)$ and ${\lambda }_2(G)$ denote the largest and the second largest adjacency eigenvalue of $G$. The sum ${\lambda }_1(G)+{\lambda }_2(G)$ is called the \emph{spectral sum} of $G$…