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[Merged by Bors] - feat(algebraic_geometry): Being quasi-compact is a local property. #15995
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erdOne
commented
Aug 11, 2022
lemma quasi_compact.affine_open_cover_tfae {X Y : Scheme.{u}} (f : X ⟶ Y) : | ||
tfae [quasi_compact f, | ||
∃ (𝒰 : Scheme.open_cover.{u} Y) [∀ i, is_affine (𝒰.obj i)], | ||
∀ (i : 𝒰.J), compact_space (pullback f (𝒰.map i)).carrier, | ||
∀ (𝒰 : Scheme.open_cover.{u} Y) [∀ i, is_affine (𝒰.obj i)] (i : 𝒰.J), | ||
compact_space (pullback f (𝒰.map i)).carrier, | ||
∀ {U : Scheme} (g : U ⟶ Y) [is_affine U] [is_open_immersion g], | ||
compact_space (pullback f g).carrier, | ||
∃ {ι : Type u} (U : ι → opens Y.carrier) (hU : supr U = ⊤) (hU' : ∀ i, is_affine_open (U i)), | ||
∀ i, compact_space (f.1.base ⁻¹' (U i).1)] := | ||
quasi_compact_eq_affine_property.symm ▸ | ||
quasi_compact_affine_property_is_local.affine_open_cover_tfae f | ||
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lemma quasi_compact.open_cover_tfae {X Y : Scheme.{u}} (f : X ⟶ Y) : | ||
tfae [quasi_compact f, | ||
∃ (𝒰 : Scheme.open_cover.{u} Y), ∀ (i : 𝒰.J), | ||
quasi_compact (pullback.snd : (𝒰.pullback_cover f).obj i ⟶ 𝒰.obj i), | ||
∀ (𝒰 : Scheme.open_cover.{u} Y) (i : 𝒰.J), | ||
quasi_compact (pullback.snd : (𝒰.pullback_cover f).obj i ⟶ 𝒰.obj i), | ||
∀ (U : opens Y.carrier), quasi_compact (f ∣_ U), | ||
∀ {U : Scheme} (g : U ⟶ Y) [is_open_immersion g], | ||
quasi_compact (pullback.snd : pullback f g ⟶ _), | ||
∃ {ι : Type u} (U : ι → opens Y.carrier) (hU : supr U = ⊤), ∀ i, quasi_compact (f ∣_ (U i))] := | ||
quasi_compact_eq_affine_property.symm ▸ | ||
quasi_compact_affine_property_is_local.target_affine_locally_is_local.open_cover_tfae f |
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Should these two be merged? Probably already at the general level of local properties?
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I don't think it is necessary. The use case of these lemmas are usually to and from quasi_compact
, and their proofs are separate as well.
Co-authored-by: Johan Commelin <johan@commelin.net>
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Thanks 🎉
bors merge
…15995) Co-authored-by: Andrew Yang <36414270+erdOne@users.noreply.github.com>
Build failed (retrying...): |
…15995) Co-authored-by: Andrew Yang <36414270+erdOne@users.noreply.github.com>
bors merge p=2 |
…15995) Co-authored-by: Andrew Yang <36414270+erdOne@users.noreply.github.com>
Pull request successfully merged into master. Build succeeded: |