diff --git a/CommAlg/jayden(krull-dim-zero).lean b/CommAlg/jayden(krull-dim-zero).lean index 0646bcb..3651102 100644 --- a/CommAlg/jayden(krull-dim-zero).lean +++ b/CommAlg/jayden(krull-dim-zero).lean @@ -4,15 +4,16 @@ import Mathlib.RingTheory.Noetherian import Mathlib.Order.KrullDimension import Mathlib.RingTheory.Artinian import Mathlib.RingTheory.Ideal.Quotient +import Mathlib.RingTheory.Nilpotent 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 +import Mathlib.Algebra.Ring.Pi +import Mathlib.Topology.NoetherianSpace -- copy from krull.lean; the name of Krull dimension for rings is changed to krullDim' since krullDim already exists in the librrary namespace Ideal @@ -26,21 +27,9 @@ noncomputable def krullDim' (R : Type) [CommRing R] : WithBot ℕ∞ := ⨆ (I : -- 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 + IsNoetherianRing R ∧ krullDim' R = 0 ↔ IsArtinianRing R := by sorry -variable {R : Type _} [CommRing R] - --- Repeats the definition by Monalisa -noncomputable def length : krullDim (Submodule _ _) - - --- The following is Stacks Lemma 10.60.5 -lemma dim_zero_Noetherian_iff_Artinian (R : Type _) [CommRing R] : - IsNoetherianRing R ∧ krull_dim R = 0 ↔ IsArtinianRing R := by - - sorry - #check IsNoetherianRing #check krullDim @@ -48,7 +37,8 @@ lemma dim_zero_Noetherian_iff_Artinian (R : Type _) [CommRing R] : -- 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) +-- change the definition of length +noncomputable def length := Set.chainHeight {M' : Submodule R M | M' < ⊤} #check length -- Stacks Lemma 10.53.6: R is Artinian iff R has finite length as an R-mod @@ -58,9 +48,42 @@ lemma IsArtinian_iff_finite_length : IsArtinianRing R ↔ ∃ n : ℕ, length R 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 +lemma Jacobson_of_Artinian_is_nilpotent : IsArtinianRing R → IsNilpotent (Ideal.jacobson (⊤ : Ideal R)) := by sorry +-- Stacks Definition 10.32.1: An ideal is locally nilpotent +-- if every element is nilpotent +namespace Ideal +class IsLocallyNilpotent (I : Ideal R) : Prop := + h : ∀ x ∈ I, IsNilpotent x + +end Ideal + +#check Ideal.IsLocallyNilpotent + +-- Stacks Lemma 10.53.5: If R has finitely many maximal ideals and +-- locally nilpotent Jacobson radical, then R is the product of its localizations at +-- its maximal ideals. Also, all primes are maximal + +lemma product_of_localization_at_maximal_ideal : Finite (MaximalSpectrum R) + ∧ Ideal.IsLocallyNilpotent (Ideal.jacobson (⊤ : Ideal R)) → Pi.commRing (MaximalSpectrum R) Localization.AtPrime R I + := by sorry +-- Haven't finished this. + +-- Stacks Lemma 10.31.5: R is Noetherian iff Spec(R) is a Noetherian space +lemma ring_Noetherian_iff_spec_Noetherian : IsNoetherianRing R + ↔ TopologicalSpace.NoetherianSpace (PrimeSpectrum R) := by sorry +-- Use TopologicalSpace.NoetherianSpace.exists_finset_irreducible : +-- Every closed subset of a noetherian space is a finite union +-- of irreducible closed subsets. + + +-- Stacks Lemma 10.26.1 (Should already exists) +-- (1) The closure of a prime P is V(P) +-- (2) the irreducible closed subsets are V(P) for P prime +-- (3) the irreducible components are V(P) for P minimal prime + +-- Stacks Lemma 10.32.5: R Noetherian. I,J ideals. If J ⊂ √I, then J ^ n ⊂ I for some n -- how to use namespace @@ -70,8 +93,6 @@ end something open something --- The following is Stacks Lemma 10.53.6 -lemma IsArtinian_iff_finite_length : IsArtinianRing R ↔ ∃ n : ℕ, length R R ≤ n := by sorry