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Top Questions
31 votes

Etale cohomology can not be computed by Cech

ag.algebraic-geometry nt.number-theory cohomology etale-cohomology cech-cohomology asked Sep 23, 2016 at 22:59
mathoverflow.net

23 votes

Is the $H$-space structure on $S^7$ associative up to homotopy?

at.algebraic-topology homotopy-theory h-spaces asked Dec 3, 2016 at 22:48
mathoverflow.net

15 votes

Lower central series quotients in terms of (co)homology

ag.algebraic-geometry at.algebraic-topology gr.group-theory group-cohomology hodge-theory asked Apr 17, 2016 at 23:30
mathoverflow.net

14 votes

Local proof of Grothendieck-Riemann-Roch theorem

ag.algebraic-geometry rt.representation-theory homological-algebra lie-algebras characteristic-classes asked May 21, 2016 at 0:36
mathoverflow.net

8 votes

Grothendieck's motivation of crystalline cohomology

ag.algebraic-geometry nt.number-theory reference-request p-adic-hodge-theory crystalline-cohomology asked Sep 30, 2016 at 23:00
mathoverflow.net

8 votes

Functorial classes in Brauer group

ag.algebraic-geometry nt.number-theory homological-algebra etale-cohomology asked Sep 22, 2016 at 0:17
mathoverflow.net

8 votes

Failure of integral comparison between crystalline and de Rham cohomology over a highly ramified base

ag.algebraic-geometry nt.number-theory p-adic-hodge-theory asked Apr 15, 2018 at 19:59
mathoverflow.net

7 votes

Arbitrarily non-degenerate Hodge to de Rham spectral sequence

ag.algebraic-geometry homological-algebra hodge-theory spectral-sequences positive-characteristic asked Jan 14, 2017 at 21:33
mathoverflow.net

7 votes

Does Chabauty-Coleman method give an algorithm for finding rational points?

ag.algebraic-geometry nt.number-theory arithmetic-geometry rational-points birch-swinnerton-dyer asked Sep 11, 2016 at 15:52
mathoverflow.net

6 votes

Multiplication in universal enveloping algebra in terms of PBW isomorphism

co.combinatorics rt.representation-theory lie-groups lie-algebras asked May 30, 2016 at 23:16
mathoverflow.net

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Top Answers
35
Crux of Dwork's proof of rationality of the zeta function?
mathoverflow.net

17
Commutative ring $R$ with no nontrivial idempotents, with a localization $R_r$ with infinitely many idempotents
mathoverflow.net

12
Question on the Sato-Tate conjecture
mathoverflow.net

11
Weaker version of Dwork's rationality of zeta function, what is needed to beef up into a complete proof?
mathoverflow.net

10
Are the Eigenvalues of the Frobenius on Crystalline cohomology bounded by degree?
mathoverflow.net

10
Printing omission in Mumford's "Lectures on Curves on an Algebraic Surface"
mathoverflow.net

10
P-adic functions on annuli
mathoverflow.net

10
Show that a field extension $L/K$ is separable iff the trace form is non-degenerate.
math.stackexchange.com

10
Can we define fundamental groups functorially for non-pointed path connected topological spaces?
mathoverflow.net

10
Are "large enough" finite etale covers arithmetic?
mathoverflow.net

10
Can non-split extension be isomorphic to the split one as objects
mathoverflow.net

9
Bundle over $\mathbb{C}^{n}\setminus{0}$
mathoverflow.net

8
Pullback along Frobenius morphism
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8
Descent a representation over finite field
mathoverflow.net

8
Any hyperelliptic curve is never a complete intersection.
math.stackexchange.com

8
Is there a version of algebraic de Rham cohomology that can be used to calculate torsion classes?
mathoverflow.net

7
Multiplicativity twisted Hochschild Kostant Rosenberg isomorphism
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6
Defining hom spaces in the derived category as limits of hom spaces in the homotopy category
mathoverflow.net

6
Elementary examples of the Weil conjectures
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6
Dominant map from affine space implies unirationality
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6
Cohomological interpretation of G-equivariant line bundles
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6
Virtual mixed Tate motives
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6
Does every section of the map Gal$(\overline{k(\!(t)\!)}/k(\!(t)\!))\rightarrow$ Gal$(\overline{k}/k)$ stabilize a compatible system of roots of $t$?
mathoverflow.net

6
Some basic questions on crystalline cohomology
mathoverflow.net

6
Lifting a splitting of an Abelian variety to characteristic 0
mathoverflow.net

6
A variant on characteristic $p$ de Rham cohomology
mathoverflow.net

6
Can Hodge symmetry fail if there is a lift to $W_2$ and the crystalline cohomology is torsion-free?
mathoverflow.net

6
Coefficients of the characteristic polynomial of the map on algebraic de Rham cohomology
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6
Vector bundles on adic spaces
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5
Does the Tate construction (defined with direct sums) have a derived interpretation?
mathoverflow.net

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