A Survey on the Laplacian-Energy-Like Invariant ∗

Abstract

Let G be a simple graph of order n ,a nd letμ1 ≥ μ2 ≥ · ·· ≥ μn =0b e the Laplacian spectrum of G. The Laplacian-energy-like invariant of G, LEL for short, is defined as LEL(G )= � n−1 i=1 √ μi. In this paper, we survey results on LEL, with