theorem Th3:
  for W be non empty Subset of V holds Funcs W c= Funcs V
proof
  let W be non empty Subset of V;
  let f be object;
  assume f in Funcs W;
  then ex A,B being Element of W st(B={} implies A={}) & f is Function of A,B
  by Th1;
  hence thesis by Th1;
end;
