+ } else if (other - self == 2
+ && is_ex_of_type(self[1], clifford)) {
+ *self = 2 - dim;
+ *other = _ex1();
+ return true;
+
+ // gamma~mu*gamma~alpha*gamma~beta*gamma.mu = 4*g~alpha~beta+(dim-4)*gamam~alpha*gamma~beta
+ } else if (other - self == 3
+ && is_ex_of_type(self[1], clifford)
+ && is_ex_of_type(self[2], clifford)) {
+ *self = 4 * metric_tensor(self[1].op(1), self[2].op(1)) * dirac_one() + (dim - 4) * self[1] * self[2];
+ self[1] = _ex1();
+ self[2] = _ex1();
+ *other = _ex1();
+ return true;
+
+ // gamma~mu*gamma~alpha*gamma~beta*gamma~delta*gamma.mu = -2*gamma~delta*gamma~beta*gamma~alpha+(4-dim)*gamma~alpha*gamma~beta*gamma~delta
+ } else if (other - self == 4
+ && is_ex_of_type(self[1], clifford)
+ && is_ex_of_type(self[2], clifford)
+ && is_ex_of_type(self[3], clifford)) {
+ *self = -2 * self[3] * self[2] * self[1] + (4 - dim) * self[1] * self[2] * self[3];
+ self[1] = _ex1();
+ self[2] = _ex1();
+ self[3] = _ex1();