-- Mathlib/GroupTheory/Perm/Cycle/PossibleTypes.lean
theorem Equiv.Perm.exists_with_cycleType_iff {m : Multiset ℕ} :
    (∃ g : Equiv.Perm α, g.cycleType = m) ↔
      (m.sum ≤ Fintype.card α ∧ ∀ a ∈ m, 2 ≤ a)

Proof state:
case h.h2
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
⊢ List.Pairwise (fun a b => a.formPerm.Disjoint b.formPerm) p

Tactic:
apply List.Pairwise.imp_of_mem _ hp_disj

Result:
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
⊢ ∀ {a b : List α}, a ∈ p → b ∈ p → a.Disjoint b → a.formPerm.Disjoint b.formPerm

Proof state:
case mpr.intro.intro.intro.intro
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
⊢ ∃ g, g.cycleType = m

Tactic:
use List.prod (List.map (fun l => List.formPerm l) p)

Result:
case h
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
⊢ (List.map (fun l => l.formPerm) p).prod.cycleType = m

Proof state:
case h.h1.intro.intro
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
x : List α
hx : x ∈ p
hx_nodup : x.Nodup
⊢ ((↑x).formPerm hx_nodup).IsCycle

Tactic:
apply Cycle.isCycle_formPerm

Result:
case h.h1.intro.intro.hn
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
x : List α
hx : x ∈ p
hx_nodup : x.Nodup
⊢ (↑x).Nontrivial

Proof state:
case h.h.h
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
⊢ ∀ a ∈ p, ((Finset.card ∘ support) ∘ fun l => l.formPerm) a = a.length

Tactic:
intro x hx

Result:
case h.h.h
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
x : List α
hx : x ∈ p
⊢ ((Finset.card ∘ support) ∘ fun l => l.formPerm) x = x.length

Proof state:
case h.h.h
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
x : List α
hx : x ∈ p
⊢ x.toFinset.card = x.length

Tactic:
rw [List.toFinset_card_of_nodup (hp_nodup x hx)]

Result:
no goals

Proof state:
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
x : List α
hx : x ∈ p
⊢ ∃ a ∈ p, a.length = x.length

Tactic:
exact ⟨x, hx, rfl⟩

Result:
no goals

Proof state:
case h.h.h
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
x : List α
hx : x ∈ p
⊢ x.formPerm.support.card = x.length

Tactic:
rw [List.support_formPerm_of_nodup x (hp_nodup x hx)]

Result:
case h.h.h
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
x : List α
hx : x ∈ p
⊢ x.toFinset.card = x.length

case h.h.h
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
x : List α
hx : x ∈ p
⊢ ∀ (x_1 : α), x ≠ [x_1]

Proof state:
case h
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
⊢ (List.map (fun l => l.formPerm) p).prod.cycleType = m

Tactic:
have hp2 : ∀ x ∈ p, 2 ≤ x.length := by
  intro x hx
  apply h2c x.length
  rw [← Multiset.mem_toList, ← hp_length, List.mem_map]
  exact ⟨x, hx, rfl⟩

Result:
case h
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
hc' : m.toList.sum ≤ Fintype.card α
p : List (List α)
hp_length : List.map List.length p = m.toList
hp_nodup : ∀ s ∈ p, s.Nodup
hp_disj : List.Pairwise List.Disjoint p
hp2 : ∀ x ∈ p, 2 ≤ x.length
⊢ (List.map (fun l => l.formPerm) p).prod.cycleType = m

Proof state:
case mpr
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
⊢ (m.sum ≤ Fintype.card α ∧ ∀ a ∈ m, 2 ≤ a) → ∃ g, g.cycleType = m

Tactic:
rintro ⟨hc, h2c⟩

Result:
case mpr.intro
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
⊢ ∃ g, g.cycleType = m

Proof state:
case mp.intro.right
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
g : Perm α
hg : g.cycleType = m
a : ℕ
⊢ a ∈ g.cycleType → 2 ≤ a

Tactic:
exact Equiv.Perm.two_le_of_mem_cycleType

Result:
no goals

Proof state:
α : Type u_1
inst✝¹ : DecidableEq α
inst✝ : Fintype α
m : Multiset ℕ
hc : m.sum ≤ Fintype.card α
h2c : ∀ a ∈ m, 2 ≤ a
⊢ m.sum ≤ Fintype.card α

Tactic:
exact hc

Result:
no goals