simp only [mem_maximals_iff, mem_setOf_eq, and_congr_right_iff]
α : Type u_1
P : Set α → Prop
hP : ∀ ⦃s t : Set α⦄, P t → s ⊆ t → P s
s : Set α
⊢ s ∈ maximals (fun x x_1 => x ⊆ x_1) {t | P t} ↔ P s ∧ ∀ x ∉ s, ¬P (insert x s)
α : Type u_1
P : Set α → Prop
hP : ∀ ⦃s t : Set α⦄, P t → s ⊆ t → P s
s : Set α
⊢ P s → ((∀ ⦃y : Set α⦄, P y → s ⊆ y → s = y) ↔ ∀ x ∉ s, ¬P (insert x s))