Equations
- Finset.fintype = { elems := Finset.powerset Finset.univ, complete := (_ : ∀ (x : Finset α), x ∈ Finset.powerset Finset.univ) }
@[simp]
theorem
Fintype.card_finset
{α : Type u_1}
[Fintype α]
:
Fintype.card (Finset α) = 2 ^ Fintype.card α
@[simp]
theorem
Finset.filter_subset_univ
{α : Type u_1}
[Fintype α]
[DecidableEq α]
(s : Finset α)
:
Finset.filter (fun t => t ⊆ s) Finset.univ = Finset.powerset s
@[simp]
theorem
Finset.powerset_eq_univ
{α : Type u_1}
[Fintype α]
{s : Finset α}
:
Finset.powerset s = Finset.univ ↔ s = Finset.univ
@[simp]
theorem
Finset.mem_powersetLen_univ
{α : Type u_1}
[Fintype α]
{s : Finset α}
{k : ℕ}
:
s ∈ Finset.powersetLen k Finset.univ ↔ Finset.card s = k
@[simp]
theorem
Finset.univ_filter_card_eq
(α : Type u_1)
[Fintype α]
(k : ℕ)
:
Finset.filter (fun s => Finset.card s = k) Finset.univ = Finset.powersetLen k Finset.univ
@[simp]
theorem
Fintype.card_finset_len
{α : Type u_1}
[Fintype α]
(k : ℕ)
:
Fintype.card { s // Finset.card s = k } = Nat.choose (Fintype.card α) k
Equations
@[simp]