diff --git a/comm_alg/grant.lean b/comm_alg/grant.lean index 86c05fc..8586fa3 100644 --- a/comm_alg/grant.lean +++ b/comm_alg/grant.lean @@ -1,12 +1,61 @@ import Mathlib.Order.KrullDimension +import Mathlib.Order.JordanHolder import Mathlib.AlgebraicGeometry.PrimeSpectrum.Basic +import Mathlib.Order.Height -def hello : IO Unit := do - IO.println "Hello, World!" - -#eval hello #check (p q : PrimeSpectrum _) → (p ≤ q) #check Preorder (PrimeSpectrum _) -#check krullDim (PrimeSpectrum _) \ No newline at end of file +-- Dimension of a ring +#check krullDim (PrimeSpectrum _) + +-- Length of a module +#check krullDim (Submodule _ _) + +#check JordanHolderLattice + + +variable {α : Type _} [Preorder α] (s : Set α) + +def finFun_to_list {n : ℕ} : (Fin n → α) → List α := by sorry + +def series_to_chain : StrictSeries s → s.subchain +| ⟨length, toFun, strictMono⟩ => + ⟨ 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 +lemma twoHeights : s ≠ ∅ → (some (Set.chainHeight s) : WithBot (WithTop ℕ)) = krullDim s := by + intro hs + unfold Set.chainHeight + unfold krullDim + have hKrullSome : ∃n, krullDim s = some n := by + + sorry + -- norm_cast + sorry + +namespace Ideal +noncomputable def krullDim (R : Type _) [CommRing R] := + Set.chainHeight (Set.univ : Set (PrimeSpectrum R)) + +def krullDimGE (R : Type _) [CommRing R] (n : ℕ) := + ∃ c : List (PrimeSpectrum R), c.Chain' (· < ·) ∧ c.length = n + 1 + +def krullDimLE (R : Type _) [CommRing R] (n : ℕ) := + ∀ c : List (PrimeSpectrum R), c.Chain' (· < ·) → c.length ≤ n + 1 + +end Ideal + +open Ideal + +lemma krullDim_le (R : Type _) [CommRing R] : krullDimLE R n ↔ Ideal.krullDim R ≤ n := sorry +lemma krullDim_ge (R : Type _) [CommRing R] : krullDimGE R n ↔ Ideal.krullDim R ≥ n := sorry + + +-- #check ((4 : ℕ∞) : WithBot (WithTop ℕ)) +#check ( (Set.chainHeight s) : WithBot (ℕ∞)) \ No newline at end of file