theorem
  z|^ 3=z*z*z & z|^ 3=z^2*z & z|^ 3 = z^3
proof
  z|^ 3 = z|^(2+1) .= z|^(1+1)*z by NEWTON:6
    .= z|^1*z*z by NEWTON:6
    .= z*z*z;
  hence thesis;
end;
