intro k hk
case refine_1
α : Type u
lt : α → α → Bool
inst✝ : LawfulLTBRel lt
x : Subarray α
⊢ ∀ (k : Nat), Subarray.size x / 2 ≤ k → IsHeap lt x k
case refine_1
α : Type u
lt : α → α → Bool
inst✝ : LawfulLTBRel lt
x : Subarray α
k : Nat
hk : Subarray.size x / 2 ≤ k
⊢ IsHeap lt x k