Let G be a simple connected graph of order n and size m, vertex degree
sequence d1 ? d2 ?...? dn > 0, and let ?1 ? ? 2 ? ... ? ?n-1 > ?n = 0
be the eigenvalues of its Laplacian matrix. Laplacian energy LE,
Laplacian-energy-like invariant LEL and Kirchhoff index Kf, are graph
invariants defined in terms of Laplacian eigenvalues. These are,
respectively, defined as LE(G) = ?n,i=1 |?i-2m/n|, LEL(G) = ?n-1
i=1 ??i and Kf (G) = n ?n-1,i=1 1/?i. A vertex-degree-based topological
index referred to as degree deviation is defined as S(G) = ?n,i=1 |di-
2m/n|. Relations between Kf and LE, Kf and LEL, as well as Kf and S are
obtained.