The following table shows where isomorphism may be generally expected.
Moreover, the isomorphism is simple unless for one or more operations, other than identity, the sets all remain unaltered.
A subgroup of a group G, which is transformed into itself by every isomorphism of G, is called a characteristic subgroup.
In the first case the isomorphism is spoken of as simple, in the second as multiple.
In this case H would contain a self-conjugate subgroup, and the isomorphism is multiple.
from German Isomorphismus, 1828, coined by German chemist Eilhard Mitscherlich (1794-1863) from isomorph; see isomorphic. Related: Isomorph.
isomorphism i·so·mor·phism (ī'sə-môr'fĭz'əm)
n.
A similarity in form, as in organisms of different ancestry.
A close similarity in the crystalline structure of two or more substances of similar chemical composition.