intros hf hle
α : Sort ?u.12184
le : α → α → Bool
not_le_le : ∀ (x y : α), ¬le x y = true → le y x = true
n : ℕ
α✝ : Type u_1
xs : List (BinTree α✝)
m : ℕ
⊢ IsHeapForest' n xs → m ≤ n → IsHeapForest' m xs
α : Sort ?u.12184
le : α → α → Bool
not_le_le : ∀ (x y : α), ¬le x y = true → le y x = true
n : ℕ
α✝ : Type u_1
xs : List (BinTree α✝)
m : ℕ
hf : IsHeapForest' n xs
hle : m ≤ n
⊢ IsHeapForest' m xs