Isomorphism

Summary

An isomorphism between two structures of the same signature is a bijection that preserves and reflects all operations, constants and relations. Two structures are isomorphic when an isomorphism between them exists; then they have the same properties expressible in their signature. Group isomorphisms, ring isomorphisms, linear isomorphisms and order isomorphisms are special cases. An isomorphism of a structure with itself is an automorphism.