diff --git a/CommAlg/krull.lean b/CommAlg/krull.lean index 7d4a31c..e26837f 100644 --- a/CommAlg/krull.lean +++ b/CommAlg/krull.lean @@ -49,10 +49,12 @@ lemma height_le_of_le {I J : PrimeSpectrum R} (I_le_J : I ≤ J) : height I ≤ show J' < J exact lt_of_lt_of_le hJ' I_le_J -lemma krullDim_le_iff (R : Type _) [CommRing R] (n : ℕ) : +@[simp] +lemma krullDim_le_iff {R : Type _} [CommRing R] {n : ℕ} : krullDim R ≤ n ↔ ∀ I : PrimeSpectrum R, (height I : WithBot ℕ∞) ≤ ↑n := iSup_le_iff (α := WithBot ℕ∞) -lemma krullDim_le_iff' (R : Type _) [CommRing R] (n : ℕ∞) : +@[simp] +lemma krullDim_le_iff' {R : Type _} [CommRing R] {n : ℕ∞} : krullDim R ≤ n ↔ ∀ I : PrimeSpectrum R, (height I : WithBot ℕ∞) ≤ ↑n := iSup_le_iff (α := WithBot ℕ∞) @[simp] @@ -91,7 +93,8 @@ lemma height_bot_eq {D: Type _} [CommRing D] [IsDomain D] : height (⊥ : PrimeS /-- The Krull dimension of a ring being ≥ n is equivalent to there being an ideal of height ≥ n. -/ -lemma le_krullDim_iff (R : Type _) [CommRing R] (n : ℕ) : +@[simp] +lemma le_krullDim_iff {R : Type _} [CommRing R] {n : ℕ} : n ≤ krullDim R ↔ ∃ I : PrimeSpectrum R, n ≤ (height I : WithBot ℕ∞) := by constructor · unfold krullDim @@ -246,7 +249,7 @@ lemma not_maximal_of_lt_prime {p : Ideal R} {q : Ideal R} (hq : IsPrime q) (h : /-- Krull dimension is ≤ 0 if and only if all primes are maximal. -/ lemma dim_le_zero_iff : krullDim R ≤ 0 ↔ ∀ I : PrimeSpectrum R, IsMaximal I.asIdeal := by show ((_ : WithBot ℕ∞) ≤ (0 : ℕ)) ↔ _ - rw [krullDim_le_iff R 0] + rw [krullDim_le_iff] constructor <;> intro h I . contrapose! h have ⟨𝔪, h𝔪⟩ := I.asIdeal.exists_le_maximal (IsPrime.ne_top I.IsPrime) @@ -353,7 +356,7 @@ lemma dim_le_one_iff : krullDim R ≤ 1 ↔ Ring.DimensionLEOne R := sorry applies only to dimension zero rings and domains of dimension 1. -/ lemma dim_le_one_of_dimLEOne : Ring.DimensionLEOne R → krullDim R ≤ 1 := by show _ → ((_ : WithBot ℕ∞) ≤ (1 : ℕ)) - rw [krullDim_le_iff R 1] + rw [krullDim_le_iff] intro H p apply le_of_not_gt intro h @@ -375,7 +378,7 @@ lemma dim_le_one_of_pid [IsDomain R] [IsPrincipalIdealRing R] : krullDim R ≤ 1 exact Ring.DimensionLEOne.principal_ideal_ring R /-- The ring of polynomials over a field has dimension one. -/ -lemma polynomial_over_field_dim_one {K : Type} [Nontrivial K] [Field K] : krullDim (Polynomial K) = 1 := by +lemma polynomial_over_field_dim_one {K : Type _} [Nontrivial K] [Field K] : krullDim (Polynomial K) = 1 := by rw [le_antisymm_iff] let X := @Polynomial.X K _ constructor