User Leonid Positselski

4 votes

Cov. right-exact additive functors that don't commute with direct sums?

answered Apr 11, 2012 at 15:02

4 votes

Accepted

Question about an exact sequence

answered Dec 16, 2012 at 0:35

4 votes

Accepted

A perfect ring that isn't semiprimary

answered Apr 30, 2018 at 21:39

4 votes

Projectives in the category of discrete G-modules

answered Mar 13, 2013 at 19:46

4 votes

Understanding Sweedler's notation for the structure map of a comodule

answered Nov 15, 2013 at 22:14

4 votes

Accepted

On two notions of 'generators' for a 'large' triangulated category

answered Jul 25, 2014 at 13:10

4 votes

When does the continuous Galois(=etale) cohomology of fields coincide with the naive one? Often true by the Bloch-Kato conjecture?

answered Jan 23, 2015 at 20:09

4 votes

On various relations between "additional axioms" for AB4 and Grothendieck abelian categories

answered Nov 7, 2017 at 20:30

4 votes

Accepted

Lie coalgebra with no finite-dimensional subcoalgebras

answered Dec 12, 2022 at 10:35

3 votes

$\operatorname{Ind}(C^I) = \operatorname{Ind}(C)^I$?

answered Oct 27, 2023 at 1:55

3 votes

Is every locally $\kappa$-presentable category, also locally $\tau$-presentable for any $\tau > \kappa$?

answered Feb 3 at 22:46

3 votes

Accepted

Why every complex of injectives is homotopically injective (provided that, the injective dimension is finite)?

answered May 21, 2013 at 15:04

3 votes

Accepted

When does cohomology of a pro-algebraic group commute with filtered colimits of coefficients?

answered Jul 23, 2020 at 16:36

3 votes

Accepted

When does $\operatorname{Ext}_C^1(M,N_i)=0$ imply $\operatorname{Ext}_C^1\left(M,\lim\limits_\longleftarrow N_i\right)=0$?

answered Aug 14, 2020 at 12:13

3 votes

Accepted

$M$ comodule if and only if $N$ and $L$ comodules

answered Dec 11, 2020 at 14:10

3 votes

Contramodule as direct limit of its finitely generated subcontramodules

answered Feb 18, 2021 at 12:14

3 votes

Contravariant right exact functor?

answered Mar 10, 2012 at 7:52

3 votes

Mathematical Advice for Interested Highschool Students

answered Jul 26, 2011 at 19:43

3 votes

Accepted

Exceptional collections and cohomological criteria for isomorphism

answered Feb 26, 2010 at 20:05

2 votes

Is the category of Banach spaces with contractions an algebraic theory?

answered Dec 11, 2009 at 11:38

2 votes

Definition of the symmetric algebra in arbitrary characteristic for graded vector spaces

answered Nov 29, 2009 at 22:41

2 votes

In which categories is every coalgebra a sum of its finite-dimensional subcoalgebras?

answered Jul 3, 2010 at 17:05

2 votes

Behavior of the projective dimension of modules in a continuous chain of extensions

answered Aug 22, 2010 at 23:06

2 votes

What category without initial object do you care about?

answered Aug 27, 2010 at 21:13

2 votes

In what sense (if any) does the cohomology of profinite groups commute with projective limits?

answered Oct 7, 2010 at 13:23

2 votes

dg objects: Z-graded vs. Z/2Z-graded

answered Sep 26, 2010 at 21:49

2 votes

Contramodule as direct limit of its finitely generated subcontramodules

answered Feb 18, 2021 at 17:40

2 votes

Accepted

Variant of co-Tor in a bimodule category

answered Mar 10, 2018 at 23:25

2 votes

Sums of injective modules, products of projective modules?

answered Jan 31, 2017 at 21:55

2 votes

Equivalent definitions of pro-unipotent coalgebras

answered Feb 10, 2023 at 9:32

Stack Exchange Network

129 Answers

Cov. right-exact additive functors that don't commute with direct sums?

Question about an exact sequence

A perfect ring that isn't semiprimary

Projectives in the category of discrete G-modules

Understanding Sweedler's notation for the structure map of a comodule

On two notions of 'generators' for a 'large' triangulated category

When does the continuous Galois(=etale) cohomology of fields coincide with the naive one? Often true by the Bloch-Kato conjecture?

On various relations between "additional axioms" for AB4 and Grothendieck abelian categories

Lie coalgebra with no finite-dimensional subcoalgebras

$\operatorname{Ind}(C^I) = \operatorname{Ind}(C)^I$?

Is every locally $\kappa$-presentable category, also locally $\tau$-presentable for any $\tau > \kappa$?

Why every complex of injectives is homotopically injective (provided that, the injective dimension is finite)?

When does cohomology of a pro-algebraic group commute with filtered colimits of coefficients?

When does $\operatorname{Ext}_C^1(M,N_i)=0$ imply $\operatorname{Ext}_C^1\left(M,\lim\limits_\longleftarrow N_i\right)=0$?

$M$ comodule if and only if $N$ and $L$ comodules

Contramodule as direct limit of its finitely generated subcontramodules

Contravariant right exact functor?

Mathematical Advice for Interested Highschool Students

Exceptional collections and cohomological criteria for isomorphism

Is the category of Banach spaces with contractions an algebraic theory?

Definition of the symmetric algebra in arbitrary characteristic for graded vector spaces

In which categories is every coalgebra a sum of its finite-dimensional subcoalgebras?

Behavior of the projective dimension of modules in a continuous chain of extensions

What category without initial object do you care about?

In what sense (if any) does the cohomology of profinite groups commute with projective limits?

dg objects: Z-graded vs. Z/2Z-graded

Contramodule as direct limit of its finitely generated subcontramodules

Variant of co-Tor in a bimodule category

Sums of injective modules, products of projective modules?

Equivalent definitions of pro-unipotent coalgebras