import Mathlib.RingTheory.Ideal.Basic import Mathlib.RingTheory.JacobsonIdeal import Mathlib.RingTheory.Noetherian import Mathlib.Order.KrullDimension import Mathlib.RingTheory.Artinian import Mathlib.RingTheory.Ideal.Quotient import Mathlib.AlgebraicGeometry.PrimeSpectrum.Basic import Mathlib.AlgebraicGeometry.PrimeSpectrum.Maximal import Mathlib.Data.Finite.Defs import Mathlib.Order.Height import Mathlib.RingTheory.DedekindDomain.Basic import Mathlib.RingTheory.Localization.AtPrime import Mathlib.Order.ConditionallyCompleteLattice.Basic -- copy from krull.lean; the name of Krull dimension for rings is changed to krullDim' since krullDim already exists in the librrary namespace Ideal variable (R : Type _) [CommRing R] (I : PrimeSpectrum R) noncomputable def height : ℕ∞ := Set.chainHeight {J : PrimeSpectrum R | J < I} noncomputable def krullDim' (R : Type) [CommRing R] : WithBot ℕ∞ := ⨆ (I : PrimeSpectrum R), height R I -- copy ends -- Stacks Lemma 10.60.5: R is Artinian iff R is Noetherian of dimension 0 lemma dim_zero_Noetherian_iff_Artinian (R : Type _) [CommRing R] : IsNoetherianRing R ∧ krullDim' R = 0 ↔ IsArtinianRing R := by sorry #check IsNoetherianRing #check krullDim -- Repeats the definition of the length of a module by Monalisa variable (M : Type _) [AddCommMonoid M] [Module R M] noncomputable def length := krullDim (Submodule R M) #check length -- Stacks Lemma 10.53.6: R is Artinian iff R has finite length as an R-mod lemma IsArtinian_iff_finite_length : IsArtinianRing R ↔ ∃ n : ℕ, length R R ≤ n := by sorry -- Stacks Lemma 10.53.3: R is Artinian iff R has finitely many maximal ideals lemma IsArtinian_iff_finite_max_ideal : IsArtinianRing R ↔ Finite (MaximalSpectrum R) := by sorry -- Stacks Lemma 10.53.4: R Artinian => Jacobson ideal of R is nilpotent lemma Jacobson_of_Artinian_is_nilpotent : Is -- how to use namespace namespace something end something open something