diff --git a/comm_alg/krull.lean b/comm_alg/krull.lean index 2a5af42..431b8f6 100644 --- a/comm_alg/krull.lean +++ b/comm_alg/krull.lean @@ -4,6 +4,7 @@ import Mathlib.RingTheory.PrincipalIdealDomain import Mathlib.RingTheory.DedekindDomain.Basic import Mathlib.RingTheory.Ideal.Quotient import Mathlib.RingTheory.Localization.AtPrime +import Mathlib.AlgebraicGeometry.PrimeSpectrum.Basic /- This file contains the definitions of height of an ideal, and the krull dimension of a commutative ring. @@ -15,22 +16,24 @@ import Mathlib.RingTheory.Localization.AtPrime developed. -/ -variable {R : Type _} [CommRing R] (I : Ideal R) +namespace Ideal -namespace ideal +variable {R : Type _} [CommRing R] (I : PrimeSpectrum R) -noncomputable def height : ℕ∞ := Set.chainHeight {J | J ≤ I ∧ J.IsPrime} +noncomputable def height : ℕ∞ := Set.chainHeight {J : PrimeSpectrum R | J ≤ I} - 1 -noncomputable def krull_dim (R : Type _) [CommRing R] := height (⊤ : Ideal R) +noncomputable def krull_dim (R : Type) [CommRing R]: WithBot ℕ∞ := ⨆ (I : PrimeSpectrum R), height I --some propositions that would be nice to be able to eventually -lemma dim_eq_zero_iff_field : krull_dim R = 0 ↔ IsField R := sorry +lemma dim_eq_zero_iff_field : krull_dim R = 0 ↔ IsField R := by sorry #check Ring.DimensionLEOne lemma dim_le_one_iff : krull_dim R ≤ 1 ↔ Ring.DimensionLEOne R := sorry -lemma dim_le_one_of_pid [IsDomain R] [IsPrincipalIdealRing R] : krull_dim R ≤ 1 := sorry +lemma dim_le_one_of_pid [IsDomain R] [IsPrincipalIdealRing R] : krull_dim R ≤ 1 := by + rw [dim_le_one_iff] + exact Ring.DimensionLEOne.principal_ideal_ring R lemma dim_le_dim_polynomial_add_one [Nontrivial R] : krull_dim R ≤ krull_dim (Polynomial R) + 1 := sorry @@ -38,7 +41,7 @@ lemma dim_le_dim_polynomial_add_one [Nontrivial R] : lemma dim_eq_dim_polynomial_add_one [Nontrivial R] [IsNoetherianRing R] : krull_dim R = krull_dim (Polynomial R) + 1 := sorry -lemma height_eq_dim_localization [Ideal.IsPrime I] : - height I = krull_dim (Localization.AtPrime I) := sorry +lemma height_eq_dim_localization : + height I = krull_dim (Localization.AtPrime I.asIdeal) := sorry -lemma height_add_dim_quotient_le_dim : height I + krull_dim (R ⧸ I) ≤ krull_dim R := sorry \ No newline at end of file +lemma height_add_dim_quotient_le_dim : height I + krull_dim (R ⧸ I.asIdeal) ≤ krull_dim R := sorry \ No newline at end of file diff --git a/comm_alg/resources.lean b/comm_alg/resources.lean index eae7c89..adcce3a 100644 --- a/comm_alg/resources.lean +++ b/comm_alg/resources.lean @@ -9,6 +9,8 @@ import Mathlib.RingTheory.Noetherian import Mathlib.RingTheory.Artinian import Mathlib.Order.Height import Mathlib.RingTheory.MvPolynomial.Basic +import Mathlib.RingTheory.Ideal.Over +import Mathlib.AlgebraicGeometry.PrimeSpectrum.Basic variable {R M : Type _} [CommRing R] [AddCommGroup M] [Module R M] @@ -44,4 +46,14 @@ variable (I : Ideal R) #check Polynomial R --this is the polynomial ring with variables indexed by ℕ #check MvPolynomial ℕ R ---hopefully there's good communication between them \ No newline at end of file +--hopefully there's good communication between them + + +--There's a preliminary version of the going up theorem +#check Ideal.exists_ideal_over_prime_of_isIntegral + +--Theorems relating primes of a ring to primes of its localization +#check PrimeSpectrum.localization_comap_injective +#check PrimeSpectrum.localization_comap_range +--Theorems relating primes of a ring to primes of a quotient +#check PrimeSpectrum.range_comap_of_surjective \ No newline at end of file