theorem Th5:
  z|^15 = z*z*z*z*z*z*z*z*z*z*z*z*z*z*z
  proof
A1: 15 = 14+1;
    z|^14 = z*z*z*z*z*z*z*z*z*z*z*z*z*z by Th4;
    hence thesis by A1,NEWTON:6;
  end;
