reserve x, y for set;
reserve D for non empty set;
reserve UN for Universe;
reserve C for Category;
reserve O for non empty Subset of the carrier of C;
reserve G,H for AddGroup;
reserve V for Group_DOMAIN;

theorem
  for f being strict Morphism of G,H holds {f} is GroupMorphism_DOMAIN of G, H
proof
  let f be strict Morphism of G,H;
  for x being Element of {f} holds x is strict Morphism of G,H by TARSKI:def 1;
  hence thesis by Th25;
end;
