Abstract
The Kirchhoff index Kf and the Laplacian-energy- like invariant LEL are two graph invariants defined in terms of the Laplacian eigenvalues. If μ1 > μ2 > . . . > μn-1 > μn = 0 are the Laplacian eigenvalues of a connected n-vertex graph, then Kf = n σn-1 i=1 1/μi and LEL = σn-1 i=1 √ μi. We examine the conditions under which Kf > LEL. Among other results we show that Kf > LEL holds for all trees, unicyclic, bicyclic, tricyclic, and tetracyclic connected graphs, except for a finite number of graphs. These exceptional graphs are determined.
| Original language | English |
|---|---|
| Pages (from-to) | 59-70 |
| Number of pages | 12 |
| Journal | Bulletin, Classe des Sciences Mathematiques et Naturelles, Sciences Mathematiques |
| Volume | 144 |
| Issue number | 37 |
| State | Published - 2012 |
Keywords
- Kirchhoff index
- Laplacian eigenvalue
- Laplacian spectrum (of graph)
- Laplacian-energy-like invariant
- LEL