n = n0 + m, m ≤ n, m + n ≤ # x ⊦ restn(m, firstn(n, x)) = firstn(n0, restn(m, x))
Used simplifier rules: n ≤ m ⊦ n0 = m - n ↔ m = n0 + n; (elim) Used terms: n, m, n0