diff --git a/CommAlg/grant.lean b/CommAlg/grant.lean index 2f3c634..2261f25 100644 --- a/CommAlg/grant.lean +++ b/CommAlg/grant.lean @@ -17,6 +17,8 @@ import CommAlg.krull #check JordanHolderLattice +section Chains + variable {α : Type _} [Preorder α] (s : Set α) def finFun_to_list {n : ℕ} : (Fin n → α) → List α := by sorry @@ -26,7 +28,6 @@ def series_to_chain : StrictSeries s → s.subchain ⟨ finFun_to_list (fun x => toFun x), sorry⟩ - -- there should be a coercion from WithTop ℕ to WithBot (WithTop ℕ) but it doesn't seem to work -- it looks like this might be because someone changed the instance from CoeCT to Coe during the port -- actually it looks like we can coerce to WithBot (ℕ∞) fine @@ -40,15 +41,62 @@ lemma twoHeights : s ≠ ∅ → (some (Set.chainHeight s) : WithBot (WithTop -- norm_cast sorry +end Chains + +section Krull + +variable (R : Type _) [CommRing R] (M : Type _) [AddCommGroup M] [Module R M] + open Ideal -lemma krullDim_le_iff' (R : Type _) [CommRing R] : +-- chain of primes +#check height + +-- lemma height_ge_iff {𝔭 : PrimeSpectrum R} {n : ℕ∞} : +-- height 𝔭 ≥ n ↔ := sorry + +lemma height_ge_iff' {𝔭 : PrimeSpectrum R} {n : ℕ∞} : +height 𝔭 > n ↔ ∃ c : List (PrimeSpectrum R), c.Chain' (· < ·) ∧ (∀ 𝔮 ∈ c, 𝔮 < 𝔭) ∧ c.length = n + 1 := by + rcases n with _ | n + . constructor <;> intro h <;> exfalso + . exact (not_le.mpr h) le_top + . -- change ∃c, _ ∧ _ ∧ ((List.length c : ℕ∞) = ⊤ + 1) at h + -- rw [WithTop.top_add] at h + tauto + have (m : ℕ∞) : m > some n ↔ m ≥ some (n + 1) := by + symm + show (n + 1 ≤ m ↔ _ ) + apply ENat.add_one_le_iff + exact ENat.coe_ne_top _ + rw [this] + unfold Ideal.height + show ((↑(n + 1):ℕ∞) ≤ _) ↔ ∃c, _ ∧ _ ∧ ((_ : WithTop ℕ) = (_:ℕ∞)) + rw [{J | J < 𝔭}.le_chainHeight_iff] + show (∃ c, (List.Chain' _ c ∧ ∀𝔮, 𝔮 ∈ c → 𝔮 < 𝔭) ∧ _) ↔ _ + have h := fun (c : List (PrimeSpectrum R)) => (@WithTop.coe_eq_coe _ (List.length c) n) + constructor <;> rintro ⟨c, hc⟩ <;> use c --<;> tauto--<;> exact ⟨hc.1, by tauto⟩ + . --rw [and_assoc] + -- show _ ∧ _ ∧ _ + --exact ⟨hc.1, _⟩ + tauto + . change _ ∧ _ ∧ (List.length c : ℕ∞) = n + 1 at hc + norm_cast at hc + tauto + +lemma krullDim_le_iff' (R : Type _) [CommRing R] {n : WithBot ℕ∞} : Ideal.krullDim R ≤ n ↔ (∀ c : List (PrimeSpectrum R), c.Chain' (· < ·) → c.length ≤ n + 1) := by sorry -lemma krullDim_ge_iff' (R : Type _) [CommRing R] : +lemma krullDim_ge_iff' (R : Type _) [CommRing R] {n : WithBot ℕ∞} : Ideal.krullDim R ≥ n ↔ ∃ c : List (PrimeSpectrum R), c.Chain' (· < ·) ∧ c.length = n + 1 := sorry - +#check (sorry : False) +#check (sorryAx) +#check (4 : WithBot ℕ∞) +#check List.sum -- #check ((4 : ℕ∞) : WithBot (WithTop ℕ)) -#check ( (Set.chainHeight s) : WithBot (ℕ∞)) \ No newline at end of file +-- #check ( (Set.chainHeight s) : WithBot (ℕ∞)) + +variable (P : PrimeSpectrum R) + +#check {J | J < P}.le_chainHeight_iff (n := 4)