Dihedron

Set of regular n-gonal dihedra
Example hexagonal dihedron on a sphere
Typeregular polyhedron or spherical tiling
Faces2 n-gons
Edgesn
Verticesn
Vertex configurationn.n
Wythoff symbol2 | n 2
Schläfli symbol{n,2}
Coxeter diagram
Symmetry groupDnh, [2,n], (*22n), order 4n
Rotation groupDn, [2,n]+, (22n), order 2n
Dual polyhedronregular n-gonal hosohedron

A dihedron is a type of polyhedron, made of two polygon faces which share the same set of n edges. In three-dimensional Euclidean space, it is degenerate if its faces are flat, while in three-dimensional spherical space, a dihedron with flat faces can be thought of as a lens, an example of which is the fundamental domain of a lens space L(p,q).[1] Dihedra have also been called bihedra,[2] flat polyhedra,[3] or doubly covered polygons.[3]

As a spherical tiling, a dihedron can exist as nondegenerate form, with two n-sided faces covering the sphere, each face being a hemisphere, and vertices on a great circle. It is regular if the vertices are equally spaced.

The dual of an n-gonal dihedron is an n-gonal hosohedron, where n digon faces share two vertices.

  1. ^ Gausmann, Evelise; Roland Lehoucq; Jean-Pierre Luminet; Jean-Philippe Uzan; Jeffrey Weeks (2001). "Topological Lensing in Spherical Spaces". Classical and Quantum Gravity. 18 (23): 5155–5186. arXiv:gr-qc/0106033. Bibcode:2001CQGra..18.5155G. doi:10.1088/0264-9381/18/23/311. S2CID 34259877.
  2. ^ Kántor, S. (2003), "On the volume of unbounded polyhedra in the hyperbolic space" (PDF), Beiträge zur Algebra und Geometrie, 44 (1): 145–154, MR 1990989, archived from the original (PDF) on 2017-02-15, retrieved 2017-02-14.
  3. ^ a b O'Rourke, Joseph (2010), Flat zipper-unfolding pairs for Platonic solids, arXiv:1010.2450, Bibcode:2010arXiv1010.2450O