# x = m + 1, n < # x ⊦ #(x \ x[n] ') = m, # x = 0, x = [], dups(x)
Used simplifier rules: ⊦ # x = 0 ↔ x = []; (s)%n ≠ 0 ⊦ m = n - 1 ↔ n = m + 1; (elim) Used terms: # x, m