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EnglishIn this paper, we first give an upper bound for the largest signless Laplacian eigenvalue of a graph and find all the extremal graphs. Secondly, we consider the second-largest signless Laplacian eigenvalue and we characterize the connected graphs whose second-largest signless Laplacian eigenvalue does not exceed 3. Furthermore, we give the signless Laplacian spectral characterization of the latter graphs. in particular, the well-known friendship graph is proved to be determined by the signless Laplacian spectrum. (C) 2010 Elsevier B.V. All rights reserved.
| Titolo: | On the two largest Q-eigenvalues of graphs |
| Autori: | |
| Data di pubblicazione: | 2010 |
| Rivista: | |
| Abstract: | In this paper, we first give an upper bound for the largest signless Laplacian eigenvalue of a graph and find all the extremal graphs. Secondly, we consider the second-largest signless Laplacian eigenvalue and we characterize the connected graphs whose second-largest signless Laplacian eigenvalue does not exceed 3. Furthermore, we give the signless Laplacian spectral characterization of the latter graphs. in particular, the well-known friendship graph is proved to be determined by the signless Laplacian spectrum. (C) 2010 Elsevier B.V. All rights reserved. |
| Handle: | http://hdl.handle.net/11570/1904545 |
| Appare nelle tipologie: | 14.a.1 Articolo su rivista |
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