reserve p,q for Rational;
reserve g,m,m1,m2,n,n1,n2 for Nat;
reserve i,i1,i2,j,j1,j2 for Integer;
reserve R for Ring, F for Field;

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