Designs, Codes and Cryptography

, Volume 65, Issue 1–2, pp 71–75 | Cite as

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

  • Aart Blokhuis
  • Andries E. Brouwer
  • Willem H. HaemersEmail author
Open Access


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.


Graph spectrum Strongly regular graph Root lattice 

Mathematics Subject Classification (2000)

05C50 05E30 05C62 


Open Access

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.


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Copyright information

© The Author(s) 2011

Authors and Affiliations

  • Aart Blokhuis
    • 1
  • Andries E. Brouwer
    • 1
  • Willem H. Haemers
    • 2
    Email author
  1. 1.Department of MathematicsEindhoven University of TechnologyEindhovenThe Netherlands
  2. 2.Department of Econometrics & O.R.Tilburg UniversityTilburgThe Netherlands

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