diff --git a/CommAlg/jayden(krull-dim-zero).lean b/CommAlg/jayden(krull-dim-zero).lean index 15dd150..921d6f8 100644 --- a/CommAlg/jayden(krull-dim-zero).lean +++ b/CommAlg/jayden(krull-dim-zero).lean @@ -16,6 +16,7 @@ import Mathlib.Order.ConditionallyCompleteLattice.Basic import Mathlib.Algebra.Ring.Pi import Mathlib.RingTheory.Finiteness import Mathlib.Util.PiNotation +import Mathlib.RingTheory.Ideal.MinimalPrime import CommAlg.krull open PiNotation @@ -43,6 +44,8 @@ class IsLocallyNilpotent {R : Type _} [CommRing R] (I : Ideal R) : Prop := #check Ideal.IsLocallyNilpotent end Ideal +def RingJacobson (R) [Ring R] := Ideal.jacobson (⊥ : Ideal R) + -- Repeats the definition of the length of a module by Monalisa variable (R : Type _) [CommRing R] (I J : Ideal R) variable (M : Type _) [AddCommMonoid M] [Module R M] @@ -169,15 +172,15 @@ abbrev Prod_of_localization := def foo : Prod_of_localization R →+* R where toFun := sorry -- invFun := sorry - left_inv := sorry - right_inv := sorry + --left_inv := sorry + --right_inv := sorry map_mul' := sorry map_add' := sorry def product_of_localization_at_maximal_ideal [Finite (MaximalSpectrum R)] - (h : Ideal.IsLocallyNilpotent (Ideal.jacobson (⊥ : Ideal R))) : - Prod_of_localization R ≃+* R := by sorry + (h : Ideal.IsLocallyNilpotent (RingJacobson R)) : + R ≃+* Prod_of_localization R := by sorry -- Stacks Lemma 10.53.6: R is Artinian iff R has finite length as an R-mod lemma IsArtinian_iff_finite_length : @@ -193,18 +196,61 @@ lemma primes_of_Artinian_are_maximal -- Lemma: Krull dimension of a ring is the supremum of height of maximal ideals +-- Lemma: X is an irreducible component of Spec(R) ↔ X = V(I) for I a minimal prime +lemma irred_comp_minmimal_prime (X) : + X ∈ irreducibleComponents (PrimeSpectrum R) + ↔ ∃ (P : minimalPrimes R), X = PrimeSpectrum.zeroLocus P := by + sorry + +-- Lemma: localization of Noetherian ring is Noetherian +-- lemma localization_of_Noetherian_at_prime [IsNoetherianRing R] +-- (atprime: Ideal.IsPrime I) : +-- IsNoetherianRing (Localization.AtPrime I) := by sorry + + -- Stacks Lemma 10.60.5: R is Artinian iff R is Noetherian of dimension 0 -lemma dim_le_zero_Noetherian_iff_Artinian (R : Type _) [CommRing R] : - IsNoetherianRing R ∧ Ideal.krullDim R ≤ 0 ↔ IsArtinianRing R := by - constructor +lemma Artinian_if_dim_le_zero_Noetherian (R : Type _) [CommRing R] : + IsNoetherianRing R ∧ Ideal.krullDim R ≤ 0 → IsArtinianRing R := by rintro ⟨RisNoetherian, dimzero⟩ rw [ring_Noetherian_iff_spec_Noetherian] at RisNoetherian + have := fun X => (irred_comp_minmimal_prime R X).mp + choose F hf using this let Z := irreducibleComponents (PrimeSpectrum R) - have Zfinite : Set.Finite Z := by + -- have Zfinite : Set.Finite Z := by -- apply TopologicalSpace.NoetherianSpace.finite_irreducibleComponents ?_ + -- sorry + --let P := fun + rw [← ring_Noetherian_iff_spec_Noetherian] at RisNoetherian + have PrimeIsMaximal : ∀ X : Z, Ideal.IsMaximal (F X X.2).1 := by + intro X + have prime : Ideal.IsPrime (F X X.2).1 := (F X X.2).2.1.1 + rw [Ideal.dim_le_zero_iff] at dimzero + exact dimzero ⟨_, prime⟩ + have JacLocallyNil : Ideal.IsLocallyNilpotent (RingJacobson R) := by sorry + let Loc := fun X : Z ↦ Localization.AtPrime (F X.1 X.2).1 + have LocNoetherian : ∀ X, IsNoetherianRing (Loc X) := by + intro X sorry - - sorry + -- apply IsLocalization.isNoetherianRing (F X.1 X.2).1 (Loc X) RisNoetherian + have Locdimzero : ∀ X, Ideal.krullDim (Loc X) ≤ 0 := by sorry + have powerannihilates : ∀ X, ∃ n : ℕ, + ((F X.1 X.2).1) ^ n • (⊤: Submodule R (Loc X)) = 0 := by sorry + have LocFinitelength : ∀ X, ∃ n : ℕ, Module.length R (Loc X) ≤ n := by + intro X + have idealfg : Ideal.FG (F X.1 X.2).1 := by + rw [isNoetherianRing_iff_ideal_fg] at RisNoetherian + specialize RisNoetherian (F X.1 X.2).1 + exact RisNoetherian + have modulefg : Module.Finite R (Loc X) := by sorry -- not sure if this is true + specialize PrimeIsMaximal X + specialize powerannihilates X + apply power_zero_finite_length R (F X.1 X.2).1 (Loc X) idealfg powerannihilates + have RingFinitelength : ∃ n : ℕ, Module.length R R ≤ n := by sorry + rw [IsArtinian_iff_finite_length] + exact RingFinitelength + +lemma dim_le_zero_Noetherian_if_Artinian (R : Type _) [CommRing R] : + IsArtinianRing R → IsNoetherianRing R ∧ Ideal.krullDim R ≤ 0 := by intro RisArtinian constructor apply finite_length_is_Noetherian @@ -213,7 +259,6 @@ lemma dim_le_zero_Noetherian_iff_Artinian (R : Type _) [CommRing R] : intro I apply primes_of_Artinian_are_maximal --- Use TopologicalSpace.NoetherianSpace.exists_finset_irreducible :