∀ {ι : Type u_1} {α : Type u_2} [inst : Ring α] [inst_1 : LinearOrder α] [IsStrictOrderedRing α] {f g : ι → α}
  {s : Set ι}, AntivaryOn f g s ↔ ∀ ⦃i : ι⦄, i ∈ s → ∀ ⦃j : ι⦄, j ∈ s → (f j - f i) * (g j - g i) ≤ 0