English
For all s,t, permutations s is permutation-equivalent to permutations t if and only if s is permutation-equivalent to t.
Русский
Для любых s,t: permutations s ~ permutations t тогда и только тогда, когда s ~ t.
LaTeX
$$$$\operatorname{permutations} s ~ \operatorname{permutations} t \ \iff\ \ s ~ t $$$$
Lean4
theorem permutations {s t : List α} (h : s ~ t) : permutations s ~ permutations t :=
(permutations_perm_permutations' _).trans <| h.permutations'.trans (permutations_perm_permutations' _).symm