
theorem Th7:
  for f be Function, i,x be set
  holds f = f +* (i,x) +* (i,f.i)
  proof
    let f be Function, i,x be set;
    thus f = f +* (i,f.i) by FUNCT_7:35
          .= f +* (i,x) +* (i,f.i) by FUNCT_7:34;
  end;
