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2 votes
1 answer
191 views

Cohomology class of fiber bundle

Suppose I have a fiber bundle $\pi: E\rightarrow B$, with fiber $F$, such that the Serre spectral sequence on cohomology is immediately degenerate. In other words, $H^*(E)=H^*(B)\otimes H^*(F)$. I ...
6 votes
1 answer
518 views

Leray spectral sequence and pullbacks

I am trying to find a reference for the following well-known result on the functoriality of the Leray spectral sequence: Let $\pi:X\to Y$ and $\pi':X'\to Y'$ be morphisms of schemes and denote by $E_2^...
3 votes
0 answers
174 views

When the Leray spectral sequences for nice compactifications give the Deligne's weight ones?

Assume that $X$ is a proper smooth variety over an algebraically closed field $k$, $U=X\setminus (\cup D_i))$ where $D_i$ are closed subvarieties such that the set-theoretic intersections of all sets ...
0 votes
0 answers
448 views

Behavior of Ext under base change

Let $x$ be a nonzerodivisor on a local Noetherian ring $(R,m).$ Let $M,N$ be finitely generated $R/xR$-modules. How to show the existence of the following exact sequence $\cdots\longrightarrow ...