45 research outputs found
Laplacian spectral characterization of some double starlike trees
A tree is called double starlike if it has exactly two vertices of degree
greater than two. Let denote the double starlike tree obtained by
attaching pendant vertices to one pendant vertex of the path and
pendant vertices to the other pendant vertex of . In this paper, we prove
that is determined by its Laplacian spectrum
Developments on Spectral Characterizations of Graphs
In [E.R. van Dam and W.H. Haemers, Which graphs are determined by their spectrum?, Linear Algebra Appl. 373 (2003), 241-272] we gave a survey of answers to the question of which graphs are determined by the spectrum of some matrix associated to the graph. In particular, the usual adjacency matrix and the Laplacian matrix were addressed. Furthermore, we formulated some research questions on the topic. In the meantime some of these questions have been (partially) answered. In the present paper we give a survey of these and other developments.2000 Mathematics Subject Classification: 05C50Spectra of graphs;Cospectral graphs;Generalized adjacency matrices;Distance-regular graphs