Webgenerator G of D(X) the Frobenius pushforward Fe ∗G generates the bounded derived category for whenever pe is larger than the codepth of X, an invariant that is a measure of the singularity of X. The conclusion holds for all positive integers e when X is locally complete intersection. The question of when one can take G = O X is also ... WebThe usual derived functor: ∀ F ∈ S h ( X), let f! F be the sheaf associated to the presheaf U ↦ { s ∈ Γ ( U × Y X, F): Supp s is proper over U } f!: S h ( X) → S h ( Y) is left exact, and …
Stalk of a pushforward sheaf in algebraic geometry
WebThe derived category of constructible sheaves. Iordan Ganev and Robin Walters June 2014 Previous talk: L8 Sheaves and their cohomology. Sheaves and their cohomology. WebThere are issues with this derived de nition: how does one compose left and right derived functors? I can’t resolve them here. We need that there is a derived pushforward, and consequently we get a long exact sequence in cohomology. See [2, Section 1.5]. Example 2.3. Say ’: Ak!Anis the inclusion of the space fx k+1 = = x n = 0gvia the ... foam family size
Section 24.29 (0FTM): Derived pushforward—The Stacks project
Web59.35 Direct images Let us define the pushforward of a presheaf. Definition 59.35.1. Let be a morphism of schemes. Let a presheaf of sets on . The direct image, or pushforward of (under ) is We sometimes write to distinguish from other direct image functors (such as usual Zariski pushforward or ). WebStack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.. Visit Stack Exchange WebSometimes we can compute the right derived functor of a composition. Suppose that be abelian categories. Let and be left exact functors. Assume that the right derived functors , , and are everywhere defined. Then there exists a canonical transformation of functors from to , see Lemma 13.14.16. This transformation need not always be an isomorphism. foam fairy toothpaste