reserve B,C,D for Category;

theorem Th28:
  for S being Contravariant_Functor of C,D, c being Object of C, d
  being Object of D st S.(id c) = id d holds (Obj S).c = d
proof
  let S be Contravariant_Functor of C,D;
  let c be Object of C, d be Object of D;
  for c being Object of C ex d being Object of D st S.(id c) = id d by Def9;
  hence thesis by CAT_1:66;
end;
