## Pappus’s Theorem and the Modular Group

- RE Schwartz
- IHES Publications Mathematiques 78 (1993…
- 2004

We say that a collection Γ of geodesics in the hyperbolic plane H 2 is a modular pattern if Γ is invariant under the modular group PSL2(Z ), if there are only finitely many PSL2(Z )–equivalence classes of geodesics in Γ, and if each geodesic in Γ is stabilized by an infinite order subgroup of PSL2(Z ). For instance, any finite union of closed geodesics on… (More)