Digon by a line segment, without affecting the overall characteristics. The cyclic groups may be obtained as rotation symmetries of polygons: the rotational symmetries of the digon provide the group C. Digon In geometry, a digon is a polygon with two sides (edges) and two vertices. Its construction is degenerate in a Euclidean plane because either the two sides would coincide or one or both would have to be curved; however, it can be easily visualised in elliptic space. A regular digon has both angles equal and both sides equal and is represented by Schläfli symbol {2}. It may be constructed
Regular skew apeirohedron Regular skew apeirohedron In geometry, a regular skew apeirohedron is an infinite regular skew polyhedron, with either skew regular faces or skew regular vertex figures. According to Coxeter, in 1926 John Flinders Petrie generalized the concept of regular skew polygons (nonplanar polygons) to finite regular skew polyhedra in 4-dimensions, and infinite regular skew apeirohedra in 3-dimensions (described here). Coxeter identified 3 forms, with planar faces and skew vertex figures, two are complements of each other. They are all named with a modified Schläfli symbol {"l","m"|"n"}, where there are "l"-gonal faces, "m" faces around each vertex, with "holes" identified as "n"-gonal