English
Flattening n copies of a cyclically reduced word preserves cyclically reduced property.
Русский
Свертка n копий циклически сокращенного слова сохраняет цикличность.
LaTeX
$$$$ \\forall n, \\mathrm{IsCyclicallyReduced}(\\mathrm{List.flatten}(\\mathrm{List.replicate} \\ n \\ L)). $$$$
Lean4
/-- Reindex a free group basis through a bijection of the indexing sets. -/
protected def reindex (b : FreeGroupBasis ι G) (e : ι ≃ ι') : FreeGroupBasis ι' G :=
ofRepr (b.repr.trans (FreeGroup.freeGroupCongr e))