e = color_T(a, 0) * color_T(a, 1) * color_T(b, 0) * color_T(b, 1);
result += check_equal_simplify(color_trace(e, 0), 2 * color_ONE(1) / 3);
result += check_equal_simplify(color_trace(e, 1), 2 * color_ONE(0) / 3);
result += check_equal_simplify(color_trace(e, 2), e);
e = color_T(a, 0) * color_T(a, 1) * color_T(b, 0) * color_T(b, 1);
result += check_equal_simplify(color_trace(e, 0), 2 * color_ONE(1) / 3);
result += check_equal_simplify(color_trace(e, 1), 2 * color_ONE(0) / 3);
result += check_equal_simplify(color_trace(e, 2), e);