Selected Topics from the Theory of Graph Energy: Hypoenergetic Graph

Snježana Majstorović, Antoaneta Klobučar, Ivan Gutman

The energy $E=E(G)$ of graph $G$ is the sum of the absolute values of the eigenvalues of G. The motivation for the introduction of this invariant comes from chemistry, where results on $E$ were obtained already in the 1940s. A graph $G$ with $n$ vertices is said to be "hypoenergetic" if $E(G)