+static unsigned color_check2()
+{
+ // checks general identities and contractions of the generators
+
+ unsigned result = 0;
+
+ idx a(symbol("a"), 8), b(symbol("b"), 8), c(symbol("c"), 8), k(symbol("k"), 8);
+ ex e;
+
+ e = color_T(k) * color_T(k);
+ result += check_equal_simplify(e, 4 * color_ONE() / 3);
+ e = color_T(k) * color_T(a) * color_T(k);
+ result += check_equal_simplify(e, -color_T(a) / 6);
+ e = color_T(k) * color_T(a) * color_T(b) * color_T(k);
+ result += check_equal_simplify(e, delta_tensor(a, b) * color_ONE() / 4 - color_T(a) * color_T(b) / 6);
+ e = color_T(k) * color_T(a) * color_T(b) * color_T(c) * color_T(k);
+ result += check_equal_simplify(e, (color_h(a, b, c) * color_ONE() / 8).expand() - color_T(a) * color_T(b) * color_T(c) / 6);
+ e = color_T(a) * color_T(b) * color_T(a) * color_T(b);
+ result += check_equal_simplify(e, -2 * color_ONE() / 9);
+ e = color_T(a) * color_T(b) * color_T(b) * color_T(a);
+ result += check_equal_simplify(e, 16 * color_ONE() / 9);
+ e = color_T(a) * color_T(b) * color_T(c) * color_T(c) * color_T(b) * color_T(a);
+ result += check_equal_simplify(e, 64 * color_ONE() / 27);
+ e = color_T(a) * color_T(b) * color_T(c) * color_T(k) * color_T(a) * color_T(k) * color_T(c) * color_T(b);
+ result += check_equal_simplify(e, -color_ONE() / 162);
+
+ return result;
+}
+
+static unsigned color_check3()
+{
+ // checks traces
+
+ unsigned result = 0;
+
+ idx a(symbol("a"), 8), b(symbol("b"), 8), c(symbol("c"), 8), k(symbol("k"), 8);
+ ex e;
+
+ e = color_ONE();
+ result += check_equal(color_trace(e), 3);
+ e = color_T(a);
+ result += check_equal(color_trace(e), 0);
+ e = color_T(a) * color_T(b);
+ result += check_equal(color_trace(e), delta_tensor(a, b) / 2);
+ e = color_T(a) * color_T(b) * color_T(c);
+ result += check_equal(color_trace(e), color_h(a, b, c) / 4);
+
+ return result;
+}
+
+unsigned exam_color()