∀ {n : ℕ} (f : Std.Tactic.BVDecide.LRAT.Internal.DefaultFormula n),
  f.assignments.size = n →
    ∀
      (acc :
        Array Std.Tactic.BVDecide.LRAT.Internal.Assignment ×
          Std.Sat.CNF.Clause (Std.Tactic.BVDecide.LRAT.Internal.PosFin n) × Bool × Bool),
      acc.1.size = n → ∀ (i : Fin n), ↑i < acc.1.size