| m < # x, n < # x ⊦ #oc(a, x[m, x[n]]) = #oc(a, x), x[m, x[n]][n] = a, a = x[m], x = [] |
⊦ x[m] ≠ a ∧ a ≠ b ∧ m < # x → #oc(a, x[m, b]) = #oc(a, x)
n < # x, m < # x ⊦ #oc(a, x[m, x[n]]) = #oc(a, x), x[m, x[n]][n] = a, a = x[m], x = [], x[m] ≠ a ∧ a ≠ x[n] ∧ m < # x
Used terms: x[n], m, x, a