English
For a Dedekind domain R with the stated hypotheses, the equivalence IsOpen(I) ↔ Finite(R/I) holds for all I.
Русский
Для дедекдиндового кольца R при данных гипотезах выполняется эквивалентность: IsOpen(I) ↔ Finite(R/I) для всех I.
LaTeX
$$$ IsOpen(I) \iff Finite(R / I) $$$
Lean4
/-- The closure of an ideal in a topological ring as an ideal. -/
protected def closure (I : Ideal R) : Ideal R :=
{
AddSubmonoid.topologicalClosure I.toAddSubmonoid with
carrier := closure I
smul_mem' := fun c _ hx => map_mem_closure (mulLeft_continuous _) hx fun _ => I.mul_mem_left c }