Lubotzky's bounded-generator expander conjecture for finite simple groups

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Let (Gi)(G_i) be the family of all non-abelian finite simple groups. A Cayley graph C(Gi,Si)\mathcal{C}(G_i,S_i) is the graph associated with the generating set SiS_i, and a family of graphs is an ϵ\epsilon-expander family when it has a uniform expansion constant ϵ>0\epsilon>0. Lubotzky's conjecture. There exist generating sets SiS_i of uniformly bounded size such that the Cayley graphs

C(Gi,Si)\mathcal{C}(G_i,S_i)

form a family of ϵ\epsilon-expanders for some fixed ϵ>0\epsilon>0. The theorem proved in the paper establishes this for alternating and symmetric groups. Further evidence comes from expander families of fixed Lie type and from logarithmic-diameter generating sets, but uniform expansion across all non-abelian finite simple groups remains open in the source.

References

Primary source

Martin Kassabov, “Symmetric Groups and Expander Graphs”, arXiv:math/0505624 (2005).

Additional references

2 papers in this index state this conjecture (2005). The statement above is taken from the most recent of them; the others are arXiv:math/0503204.

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