Regularity and the Generalized Adjacency Spectra of Graphs

A.A. Chesnokov, W.H. Haemers

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For every rational number x 2 (0; 1), we construct a pair of graphs one regular and one nonregular with adjacency matrices A1 and A2, having the property that A1-xJ and A2-xJ have the same spectrum (J is the all-ones matrix). This solves a problem of Van Dam and the second author.For some values of x, we have generated the smallest examples (with respect to the number of vertices) by computer.
Original languageEnglish
Place of PublicationTilburg
PublisherOperations research
Number of pages6
Publication statusPublished - 2005

Publication series

NameCentER Discussion Paper


  • graphs
  • matrices


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