English
A fundamental system of units is obtained by mapping Fin(rank K) to 𝓞 K units via quotient lifting.
Русский
Фундаментальная система единиц получается через отображение Fin(rank K) к единицам 𝓞 K через подъём по фактор-группе.
LaTeX
$$fundSystem : Fin (rank K) → (𝓞 K)ˣ$$
Lean4
/-- A fundamental system of units of `K`. The units of `fundSystem` are arbitrary lifts of the
units in `basisModTorsion`. -/
def fundSystem : Fin (rank K) → (𝓞 K)ˣ :=
-- `:)` prevents the `⧸` decaying to a quotient by `leftRel` when we unfold this later
fun i ↦ Quotient.out ((basisModTorsion K i).toMul :)