This article defines a natural context where a group occurs, or is associated, with another algebraic, topological or analytic structure
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The self-homeomorphism group of a topological space is defined in any of the following ways:
- The elements of this group are homeomorphisms from the topological space to itself and the multiplication is by composition
- It is the automorphism group of the topological space when viewed as an object in the category of topological spaces with continuous maps
The self-homeomorphism group of any topological space can be given the structure of a topological group using the compact-open topology.
For a homogeneous space, the topological space can be viewed, set-theoretically, as a quotient of the self-homeomorphism group by the isotropy at any point (because there is only one orbit). This follows from the fundamental theorem of group actions. (Note: Please don't confuse isotropy (the stabilizer) with isotopy).
Particular examples are manifolds, which are always homogeneous.