English
Two permutations σ and τ are conjugate if and only if they have the same cycle partition: σ.partition = τ.partition.
Русский
Две перестановки σ и τ сопряжены тогда и только тогда, когда имеют одинаковое разбиение на циклы: σ.partition = τ.partition.
LaTeX
$$$\IsConj(σ, τ) \iff σ.partition = τ.partition$$$
Lean4
theorem partition_eq_of_isConj {σ τ : Perm α} : IsConj σ τ ↔ σ.partition = τ.partition :=
by
rw [isConj_iff_cycleType_eq]
refine ⟨fun h => ?_, fun h => ?_⟩
· rw [Nat.Partition.ext_iff, parts_partition, parts_partition, ← sum_cycleType, ← sum_cycleType, h]
· rw [← filter_parts_partition_eq_cycleType, ← filter_parts_partition_eq_cycleType, h]