New answers tagged sheaf-theory
1
vote
Canonical product in sheaf cohomology
For an approach that doesn't use any kind of Kunneth principle and is amenable, once you've established the basics, for "easy" verification of formulae consult Iversen's discussion in his ...
- 761
3
votes
Accepted
(Derived category of) sheaves over an infinite union
An easier argument would be that $R^q\pi_\ast \mathbf Q$ vanishes for $q\notin \{0,3\}$ and has rank $1$ for $q \in \{0,3\}$. Indeed, just check this on stalks. Then the cone of $\mathbf Q\to R\pi_\...
- 39.3k
4
votes
Accepted
Etale cohomology of relative elliptic curve
This will follow from the conjunction of three fundamental facts:
(1) The pushforward of a (locally) constant $\mathbb Q_p$-sheaf along a smooth proper morphism of schemes where $p$ is invertible is ...
- 137k
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