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orbifold
EntityQ40460· pop 12· linked from 366 articles

Also known as orbit-manifold

alt=Hyperbolic symmetry comparison to Euclidean symmetry|thumb|23star Orbifold Example In the mathematical disciplines of topology and geometry, an orbifold (for "orbit-manifold") is a generalization of a manifold. Roughly speaking, an orbifold is a topological space that is locally a finite group quotient of a Euclidean space.

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28 sections
Contents
  • Formal definitions
  • Definition using orbifold atlas
  • Definition using Lie groupoids
  • Relation between the two definitions
  • Examples
  • Orbifold fundamental group
  • Orbifolds as diffeologies
  • Orbispaces
  • Complexes of groups
  • Definition
  • Example
  • Edge-path group
  • Developable complexes
  • Orbihedra
  • Definition
  • Main properties
  • Triangles of groups
  • Mumford's example
  • Generalizations
  • Two-dimensional orbifolds
  • 3-dimensional orbifolds
  • Applications
  • Orbifolds in string theory
  • Calabi–Yau manifolds
  • Music theory
  • See also
  • Notes
  • References

alt=Hyperbolic symmetry comparison to Euclidean symmetry|thumb|23star Orbifold Example In the mathematical disciplines of topology and geometry, an orbifold (for "orbit-manifold") is a generalization of a manifold. Roughly speaking, an orbifold is a topological space that is locally a finite group quotient of a Euclidean space.

Definitions of orbifold have been given several times: by Ichirō Satake in the context of automorphic forms in the 1950s under the name V-manifold; by William Thurston in the context of the geometry of 3-manifolds in the 1970s when he coined the name orbifold, after a vote by his students; and by André Haefliger in the 1980s in the context of Mikhail Gromov's programme on CAT(k) spaces under the name orbihedron.

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