Designs, Codes and Cryptography

, Volume 65, Issue 1, pp 71–75

The graph with spectrum 141 240 (−4)10 (−6)9

Authors

  • Aart Blokhuis
    • Department of MathematicsEindhoven University of Technology
  • Andries E. Brouwer
    • Department of MathematicsEindhoven University of Technology
    • Department of Econometrics & O.R.Tilburg University
Open AccessArticle

DOI: 10.1007/s10623-011-9529-6

Cite this article as:
Blokhuis, A., Brouwer, A.E. & Haemers, W.H. Des. Codes Cryptogr. (2012) 65: 71. doi:10.1007/s10623-011-9529-6
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Abstract

We show that there is a unique graph with spectrum as in the title. It is a subgraph of the McLaughlin graph. The proof uses a strong form of the eigenvalue interlacing theorem to reduce the problem to one about root lattices.

Keywords

Graph spectrumStrongly regular graphRoot lattice

Mathematics Subject Classification (2000)

05C5005E3005C62
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Copyright information

© The Author(s) 2011