On comparison between the distance energies of a connected graph

Heliyon. 2024 Nov 13;10(22):e40316. doi: 10.1016/j.heliyon.2024.e40316. eCollection 2024 Nov 30.

Abstract

Let G be a simple connected graph of order n having Wiener index W ( G ) . The distance, distance Laplacian and the distance signless Laplacian energies of G are respectively defined as D E ( G ) = i = 1 n | υ i D | , D L E ( G ) = i = 1 n | υ i L - T r | and D S L E ( G ) = i = 1 n | υ i Q - T r | , where υ i D , υ i L and υ i Q , 1 i n are respectively the distance, distance Laplacian and the distance signless Laplacian eigenvalues of G and T r = 2 W ( G ) n is the average transmission degree. In this paper, we will study the relation between D E ( G ) , D L E ( G ) and D S L E ( G ) . We obtain some necessary conditions for the inequalities D L E ( G ) D S L E ( G ) , D L E ( G ) D S L E ( G ) , D L E ( G ) D E ( G ) and D S L E ( G ) D E ( G ) to hold. We will show for graphs with one positive distance eigenvalue the inequality D S L E ( G ) D E ( G ) always holds. Further, we will show for the complete bipartite graphs the inequality D L E ( G ) D S L E ( G ) D E ( G ) holds. We end this paper by computational results on graphs of order at most 6.

Keywords: 05C12; 05C50; 15A18; Distance (signless) Laplacian energy; Distance Laplacian matrix; Distance matrix; Transmission regular graph.