theorem Th4:
  z|^14 = z*z*z*z*z*z*z*z*z*z*z*z*z*z
  proof
A1: 14 = 13+1;
    z|^13 = z*z*z*z*z*z*z*z*z*z*z*z*z by Th3;
    hence thesis by A1,NEWTON:6;
  end;
