⊦ x = y ↔ # x = # y ∧ (∀ n. n < # x → x[n] = y[n])
Used simplifier rules: length-to: ¬ # x < n ⊦ #(x to n) = n;% ⊦ m ≤ n → (n < m ↔ false); (s)% ⊦ # [] = 0; (s) Used terms: [], x to n