Ramanujan Graphs with Small Girth
Abstract
Description
We construct an infinite family of (q+1)-regular Ramanujan graphs X_n of girth 1. We also give covering maps X_{n+1} --> X_n such that the minimal common covering of all the graphs is the universal covering tree.
14 pages, 1 figure. to appear: Combinatorica
14 pages, 1 figure. to appear: Combinatorica