diff --git a/CommAlg/sayantan.lean b/CommAlg/sayantan.lean index b2fc79a..6140db5 100644 --- a/CommAlg/sayantan.lean +++ b/CommAlg/sayantan.lean @@ -57,9 +57,19 @@ lemma isField.dim_zero {D: Type _} [CommRing D] [IsDomain D] (h: krullDim D = 0) simp [height] at h by_contra x rw [Ring.not_isField_iff_exists_prime] at x - obtain ⟨P, ⟨h, primeP⟩⟩ := x - have PgtBot : P > ⊥ := Ne.bot_lt h - sorry + obtain ⟨P, ⟨h1, primeP⟩⟩ := x + have PgtBot : P > ⊥ := Ne.bot_lt h1 + have pos_height : ↑(Set.chainHeight {J | J < P}) > 0 := by + have : ⊥ ∈ {J | J < P} := PgtBot + have : {J | J < P}.Nonempty := Set.nonempty_of_mem this + -- have : {J | J < P} ≠ ∅ := Set.Nonempty.ne_empty this + rw [←Set.one_le_chainHeight_iff] at this + exact Iff.mp ENat.one_le_iff_pos this + have zero_height : ↑(Set.chainHeight {J | J < P}) = 0 := by + -- Probably need to use Sup_le or something here + sorry + have : ↑(Set.chainHeight {J | J < P}) ≠ 0 := Iff.mp pos_iff_ne_zero pos_height + contradiction lemma dim_eq_zero_iff_field {D: Type _} [CommRing D] [IsDomain D] : krullDim D = 0 ↔ IsField D := by constructor