Displaying similar documents to “Modular elements in congruence lattices of G -sets.”

Modular embeddings and rigidity for Fuchsian groups

Robert A. Kucharczyk (2015)

Acta Arithmetica

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We prove a rigidity theorem for semiarithmetic Fuchsian groups: If Γ₁, Γ₂ are two semiarithmetic lattices in PSL(2,ℝ ) virtually admitting modular embeddings, and f: Γ₁ → Γ₂ is a group isomorphism that respects the notion of congruence subgroups, then f is induced by an inner automorphism of PGL(2,ℝ ).