Non-negative spectrum of a digraph

Irena M. Jovanović

Abstract


Digraphs are considered by means of eigenvalues of the matrix AAT, and similarly ATA, where A is the adjacency matrix of a digraph. The common spectrum of these matrices is called non-negative spectrum or N-spectrum of a digraph. Several properties of the N-spectrum are proved. The notion of cospectrality is generalized, and some examples of cospectral (multi)(di)graphs are constructed.


Keywords


Digraph, non-negative spectrum, multigraph, cospectrality, isomorphism

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ISSN: 1855-3974

Issues from Vol 6, No 1 onward are partially supported by the Slovenian Research Agency from the Call for co-financing of scientific periodical publications