let G, H be Ring; :: thesis: for f being Morphism of G,H holds {f} is RingMorphism_DOMAIN of G,H
let f be Morphism of G,H; :: thesis: {f} is RingMorphism_DOMAIN of G,H
for x being Element of {f} holds x is Morphism of G,H by TARSKI:def 1;
hence {f} is RingMorphism_DOMAIN of G,H by Th13; :: thesis: verum