constructor
case a
α : Type u_1
inst✝ : LinearOrder α
s U V : Finset α
n r k i : ℕ
𝒜 𝒞✝ : Finset (Finset (Fin n))
hir : i ≤ r
hrk : r ≤ k
hkn : k ≤ n
h₁ : Set.Sized r ↑𝒜
h₂ : k.choose r ≤ 𝒜.card
range'k : Finset (Fin n) := (range k).attachFin ⋯
𝒞 : Finset (Finset (Fin n)) := powersetCard r range'k
Ccard : 𝒞.card = k.choose r
this : Set.Sized r ↑𝒞
B : Finset (Fin n)
⊢ (∃ s ∈ 𝒞, B ⊆ s ∧ (s \ B).card = i) ↔ B ⊆ range'k ∧ B.card = r - i
case a.mp
α : Type u_1
inst✝ : LinearOrder α
s U V : Finset α
n r k i : ℕ
𝒜 𝒞✝ : Finset (Finset (Fin n))
hir : i ≤ r
hrk : r ≤ k
hkn : k ≤ n
h₁ : Set.Sized r ↑𝒜
h₂ : k.choose r ≤ 𝒜.card
range'k : Finset (Fin n) := (range k).attachFin ⋯
𝒞 : Finset (Finset (Fin n)) := powersetCard r range'k
Ccard : 𝒞.card = k.choose r
this : Set.Sized r ↑𝒞
B : Finset (Fin n)
⊢ (∃ s ∈ 𝒞, B ⊆ s ∧ (s \ B).card = i) → B ⊆ range'k ∧ B.card = r - i

case a.mpr
α : Type u_1
inst✝ : LinearOrder α
s U V : Finset α
n r k i : ℕ
𝒜 𝒞✝ : Finset (Finset (Fin n))
hir : i ≤ r
hrk : r ≤ k
hkn : k ≤ n
h₁ : Set.Sized r ↑𝒜
h₂ : k.choose r ≤ 𝒜.card
range'k : Finset (Fin n) := (range k).attachFin ⋯
𝒞 : Finset (Finset (Fin n)) := powersetCard r range'k
Ccard : 𝒞.card = k.choose r
this : Set.Sized r ↑𝒞
B : Finset (Fin n)
⊢ B ⊆ range'k ∧ B.card = r - i → ∃ s ∈ 𝒞, B ⊆ s ∧ (s \ B).card = i