Quasicoherence of internal Hom from a finite locally free sheaf #
For a locally free sheaf of finite type M and a quasicoherent sheaf N, the sheaf
𝓗om(M, N) is quasicoherent. The target need not be of finite type. This allows the ordinary
sheaf internal Hom from a finite locally free source to restrict to quasicoherent sheaves.
The proof uses the canonical dual-tensor comparison from TauCeti.dualTensorIhom, the finite
local freeness of 𝓗om(M, 𝒪) from SheafOfModules.isFiniteLocallyFree_ihom_unit, and closure
of quasicoherence under tensor products.
instance
SheafOfModules.isQuasicoherent_ihom_of_isLocallyFree
{C : Type u}
[CategoryTheory.SmallCategory C]
[CategoryTheory.Limits.HasPullbacks C]
{J : CategoryTheory.GrothendieckTopology C}
[J.HasSheafCompose (CategoryTheory.forget₂ CommRingCat RingCat)]
[CategoryTheory.HasWeakSheafify J AddCommGrpCat]
[J.WEqualsLocallyBijective AddCommGrpCat]
[∀ (X : C), (J.over X).HasSheafCompose (CategoryTheory.forget₂ CommRingCat RingCat)]
[∀ (X : C), CategoryTheory.HasSheafify (J.over X) AddCommGrpCat]
[∀ (X : C), (J.over X).WEqualsLocallyBijective AddCommGrpCat]
[∀ (X : C) (Y : CategoryTheory.Over X), CategoryTheory.HasSheafify ((J.over X).over Y) AddCommGrpCat]
[∀ (X : C) (Y : CategoryTheory.Over X), ((J.over X).over Y).WEqualsLocallyBijective AddCommGrpCat]
{R : CategoryTheory.Sheaf J CommRingCat}
(M N : SheafOfModules (TauCeti.SheafOfModules.ringCatSheaf R))
[M.IsLocallyFree]
[M.IsFiniteType]
[N.IsQuasicoherent]
:
(M ⟹ N).IsQuasicoherent
Internal Hom from a locally free sheaf of finite type into a quasicoherent sheaf is quasicoherent. No finiteness hypothesis is required on the target.