Cubic Ramanujan graphs


A fimily of cubic Ramanujan graph is explicitly constructed. They are realized as Cayley graphs of a certain free group acting on the 3-regular tree; this group is obtained from a definite quaternion algebra that splits at the prime 2 and has a maximal order of class number 1.

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Chiu, P. Cubic Ramanujan graphs. Combinatorica 12, 275–285 (1992).

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AMS Subject Classification code (1991)

  • 05 C 35