{α : Type u} →
  {β : Type v} →
    [inst : Preorder α] →
      [inst_1 : Preorder β] →
        {f : α → β} → {s : Set α} → [i : Decidable (∀ a ∈ s, ∀ b ∈ s, a < b → f b < f a)] → Decidable (StrictAntiOn f s)