User Torsten Ekedahl

12 votes

Torsion for Lie algebras and Lie groups

answered Jun 4, 2011 at 8:50

12 votes

Accepted

Is the functor of divided powers a weakly monoidal functor?

answered Mar 27, 2011 at 13:26

12 votes

Accepted

Top chern class in positive characteristic

answered Nov 11, 2011 at 18:57

12 votes

A ring such that all projectives are stably free but not all projectives are free?

answered Jun 8, 2010 at 6:53

12 votes

Accepted

Fixed Point Property in Algebraic Geometry

answered Mar 16, 2010 at 21:54

12 votes

Request: intermediate-level proof: every 2-homology class of a 4-manifold is generated by a surface.

answered Apr 25, 2010 at 5:27

12 votes

Accepted

Special divisors on hyperelliptic curves

answered Apr 21, 2010 at 7:17

12 votes

What is the etymology of the term "perverse sheaf"?

answered Jun 30, 2010 at 5:48

11 votes

Accepted

Leray-Hirsch principle for étale cohomology

answered Jun 23, 2010 at 5:00

11 votes

Accepted

Group Completions and Infinite-Loop Spaces

answered Aug 29, 2010 at 6:54

11 votes

Accepted

Topological dimension versus cohomological dimension

answered Oct 24, 2010 at 17:42

11 votes

Accepted

Can a non-algebraic complex manifold be embedded meromorphically into projective space?

answered Apr 19, 2010 at 12:07

11 votes

Is a field uniquely determined by its multiplicative group/how much knows K_1 about fields?

answered Apr 23, 2010 at 10:00

11 votes

Accepted

Line bundles with integrable connection on abelian varieties

answered Nov 7, 2011 at 8:49

10 votes

What are the automorphism groups of (principally polarized) abelian varieties?

answered May 8, 2011 at 18:09

10 votes

Accepted

What is the replacement for a "sufficiently small disc" in characteristic p?

answered Jun 24, 2011 at 7:33

10 votes

Accepted

Sheaves over simplicial sets

answered Mar 18, 2010 at 6:23

10 votes

Accepted

Are centrally extended p-adic groups defined over F_1?

answered May 13, 2010 at 19:25

10 votes

Commutator subgroup does not consist only of commutators?

answered Nov 7, 2010 at 14:30

10 votes

Accepted

Multiplication by $n$ on commutative algebraic groups

answered Oct 18, 2010 at 16:13

10 votes

Accepted

How does Schlessinger's criterion sit with Grothendieck Existence (aka GFGA)?

answered Jan 27, 2011 at 16:17

10 votes

Accepted

Proper holomorphic map from unit disk to punctured unit disk

answered Jan 30, 2011 at 15:57

10 votes

Accepted

Can the class of the canonical bundle be recovered from the total space of the cotangent bundle if one forgets that it is a cotangent bundle?

answered Jan 6, 2011 at 9:07

10 votes

Accepted

Comparing algebraic group orbits over big and small algebraically closed fields

answered Dec 19, 2010 at 17:12

9 votes

Square of an elliptic curve and projective plane

answered Aug 17, 2010 at 4:50

9 votes

Splitting of the Universal Coefficients sequence

answered Jun 13, 2010 at 5:24

9 votes

Accepted

The cohomology of a product of sheaves and a plea.

answered Jun 16, 2010 at 15:29

9 votes

The etale fundamental group of a field

answered Apr 18, 2010 at 5:25

9 votes

Simplest example of jumping of cohomology of structure sheaf in smooth families?

answered Jul 25, 2011 at 7:38

9 votes

Does every finite flat group scheme become constant after finite base change?

answered May 12, 2011 at 9:37

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203 Answers

Torsion for Lie algebras and Lie groups

Is the functor of divided powers a weakly monoidal functor?

Top chern class in positive characteristic

A ring such that all projectives are stably free but not all projectives are free?

Fixed Point Property in Algebraic Geometry

Request: intermediate-level proof: every 2-homology class of a 4-manifold is generated by a surface.

Special divisors on hyperelliptic curves

What is the etymology of the term "perverse sheaf"?

Leray-Hirsch principle for étale cohomology

Group Completions and Infinite-Loop Spaces

Topological dimension versus cohomological dimension

Can a non-algebraic complex manifold be embedded meromorphically into projective space?

Is a field uniquely determined by its multiplicative group/how much knows K_1 about fields?

Line bundles with integrable connection on abelian varieties

What are the automorphism groups of (principally polarized) abelian varieties?

What is the replacement for a "sufficiently small disc" in characteristic p?

Sheaves over simplicial sets

Are centrally extended p-adic groups defined over F_1?

Commutator subgroup does not consist only of commutators?

Multiplication by $n$ on commutative algebraic groups

How does Schlessinger's criterion sit with Grothendieck Existence (aka GFGA)?

Proper holomorphic map from unit disk to punctured unit disk

Can the class of the canonical bundle be recovered from the total space of the cotangent bundle if one forgets that it is a cotangent bundle?

Comparing algebraic group orbits over big and small algebraically closed fields

Square of an elliptic curve and projective plane

Splitting of the Universal Coefficients sequence

The cohomology of a product of sheaves and a plea.

The etale fundamental group of a field

Simplest example of jumping of cohomology of structure sheaf in smooth families?

Does every finite flat group scheme become constant after finite base change?