An isomorphism (isomorphic mapping) of a system of objects onto itself. The totality of all automorphisms of an arbitrary algebraic system forms a group, and the study of this group is an important and powerful tool in the study of the properties of the system itself (cf. Algebraic system, automorphism of an).
Automorphism. Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Automorphism&oldid=12546