n0 ∈ ar.indicesWhere(φ, n), n ≤ # ar, # ar ≤ n0, n ≤ n0 ⊦
Used simplifier rules: let: ⊦ n ≤ n0 ∧ n0 ≤ n1 → n ≤ n1; (forward) from specification nat% ⊦ m < n ↔ ¬ n ≤ m; (ss)