simp only [← any_nonEmpty_iff_exists_mem]
α✝ : Type
g : CNF α✝
⊢ (¬∃ a, mem a g) ↔ ∃ n, g = List.replicate n []
α✝ : Type
g : CNF α✝
⊢ ¬(List.any g fun c => !List.isEmpty c) = true ↔ ∃ n, g = List.replicate n []