English
For any natural n, the n-th power of mk L equals mk of the flattened n-fold replication of L.
Русский
Для любого натурального n степень n элемента mk L равна mk(сплющиванию n раз L).
LaTeX
$$$\\mk L\\,^n = \\mk(\\text{List.flatten}(\\text{List.replicate } n\\; L))$$$
Lean4
@[to_additive (attr := simp)]
theorem pow_mk (n : ℕ) : mk L ^ n = mk (List.flatten <| List.replicate n L) :=
match n with
| 0 => rfl
| n + 1 => by rw [pow_succ', pow_mk, mul_mk, List.replicate_succ, List.flatten_cons]