let R be Ring; :: thesis: for S being R -isomorphic Ring holds R is S -isomorphic
let S be R -isomorphic Ring; :: thesis: R is S -isomorphic
( the Isomorphism of R,S " is additive & the Isomorphism of R,S " is multiplicative & the Isomorphism of R,S " is unity-preserving & the Isomorphism of R,S " is monomorphism & the Isomorphism of R,S " is epimorphism ) by Th72;
hence R is S -isomorphic ; :: thesis: verum