theorem
  for a,b being Object of 1Cat(o,m) for f being Morphism of 1Cat(o,m)
  holds f is Morphism of a,b
proof
  let a,b be Object of 1Cat(o,m);
  let f be Morphism of 1Cat(o,m);
  f in Hom(a,b) by Th9;
  hence thesis by Def3;
end;
