Theorem: Equiv.Perm.cycle_is_cycleOf
File: Mathlib/GroupTheory/Perm/Cycle/Factors.lean

Proof steps:
state_before: ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
⊢ c = f.cycleOf a
state_after: ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
⊢ f.cycleOf a = c.cycleOf a
tactic: suffices f.cycleOf a = c.cycleOf a by
    rw [this]
    apply symm
    exact
      Equiv.Perm.IsCycle.cycleOf_eq (Equiv.Perm.mem_cycleFactorsFinset_iff.mp hc).left
        (Equiv.Perm.mem_support.mp ha)
state_before: ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
⊢ f.cycleOf a = c.cycleOf a
state_after: ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
hfc : c.Disjoint (f * c⁻¹) := Disjoint.symm (disjoint_mul_inv_of_mem_cycleFactorsFinset hc)
⊢ f.cycleOf a = c.cycleOf a
tactic: let hfc := (Equiv.Perm.disjoint_mul_inv_of_mem_cycleFactorsFinset hc).symm
state_before: ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
hfc : c.Disjoint (f * c⁻¹) := Disjoint.symm (disjoint_mul_inv_of_mem_cycleFactorsFinset hc)
⊢ f.cycleOf a = c.cycleOf a
state_after: ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
hfc : c.Disjoint (f * c⁻¹) := Disjoint.symm (disjoint_mul_inv_of_mem_cycleFactorsFinset hc)
hfc2 : Commute c (f * c⁻¹) := Disjoint.commute hfc
⊢ f.cycleOf a = c.cycleOf a
tactic: let hfc2 := Perm.Disjoint.commute hfc
state_before: ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
hfc : c.Disjoint (f * c⁻¹) := Disjoint.symm (disjoint_mul_inv_of_mem_cycleFactorsFinset hc)
hfc2 : Commute c (f * c⁻¹) := Disjoint.commute hfc
⊢ f.cycleOf a = c.cycleOf a
state_after: ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
hfc : c.Disjoint (f * c⁻¹) := Disjoint.symm (disjoint_mul_inv_of_mem_cycleFactorsFinset hc)
hfc2 : Commute c (f * c⁻¹) := Disjoint.commute hfc
⊢ f.cycleOf a = (c * (f * c⁻¹)).cycleOf a

case hx
ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
hfc : c.Disjoint (f * c⁻¹) := Disjoint.symm (disjoint_mul_inv_of_mem_cycleFactorsFinset hc)
hfc2 : Commute c (f * c⁻¹) := Disjoint.commute hfc
⊢ (f * c⁻¹) a = a
tactic: rw [← Equiv.Perm.cycleOf_mul_of_apply_right_eq_self hfc2]
state_before: case hx
ι : Type u_1
α : Type u_2
β : Type u_3
inst✝¹ : DecidableEq α
inst✝ : Fintype α
f✝ f c : Perm α
a : α
ha : a ∈ c.support
hc : c ∈ f.cycleFactorsFinset
hfc : c.Disjoint (f * c⁻¹) := Disjoint.symm (disjoint_mul_inv_of_mem_cycleFactorsFinset hc)
hfc2 : Commute c (f * c⁻¹) := Disjoint.commute hfc
⊢ (f * c⁻¹) a = a
state_after: no goals
tactic: exact
    Equiv.Perm.not_mem_support.mp
      (Finset.disjoint_left.mp (Equiv.Perm.Disjoint.disjoint_support hfc) ha)