Angle Combinations in Tilings of the Sphere by Angle Congruent Pentagons

Abstract

We develop a systematic method for deriving the angle combinations at all vertices in an edge-to-edge tiling of the sphere by pentagons with the same five angles. The method provides an effective and necessary tool in solving many tiling problems about pentagonal tilings of the sphere. More significantly, we determine all the angle combinations that allow free and continuous choices of two angle values.