1.II.12F

Geometry and Groups
Part II, 2006

Compute the area of the ball of radius rr around a point in the hyperbolic plane. Deduce that, for any tessellation of the hyperbolic plane by congruent, compact tiles, the number of tiles which are at most nn "steps" away from a given tile grows exponentially in nn. Give an explicit example of a tessellation of the hyperbolic plane.