User Yosemite Sam

23 votes

3 answers

3k views

how to make the category of chain complexes into an $\infty$-category

asked Apr 13, 2012 at 15:57

18 votes

1 answer

2k views

can a common mortal understand why the affine line is not smooth in brave new algebraic geometry?

asked Nov 17, 2011 at 16:43

14 votes

2 answers

3k views

what is the stringy Kähler moduli space?

asked May 16, 2012 at 7:39

11 votes

1 answer

1k views

coarse moduli space and $\pi_0$

asked Mar 12, 2012 at 10:30

11 votes

3 answers

1k views

Reference for the derived category of $X$, $[X/G]$ and $X/G$

asked Nov 15, 2011 at 23:24

9 votes

1 answer

3k views

surjective morphism of schemes or epimorphism of sheaves?

asked Oct 27, 2011 at 13:27

7 votes

1 answer

2k views

What is the negative cyclic homology of a smooth projective variety?

asked Nov 17, 2016 at 5:45

5 votes

0 answers

458 views

where to learn K-group of coherent sheaves modulo numerical equivalence?

asked Mar 19, 2012 at 18:44

5 votes

0 answers

209 views

Description of flop as graded algebra

asked Jun 20, 2017 at 3:47

5 votes

1 answer

712 views

Resolutions by free Differential Graded Algebras

asked Nov 1, 2016 at 3:19

4 votes

1 answer

879 views

Colimits in colimits of categories

asked Jan 21, 2017 at 15:45

4 votes

2 answers

834 views

If $f: X \to Y$ is a finite flat morphism of schemes, $g: Y \to Z$ is a proper morphism of relative dimension one, $Z$ is affine and $E$ is a vector bundle on $Y$ with $R^1g_E=0$ then $H^1(X,f^E)=0$?

asked Feb 8, 2012 at 23:48

4 votes

1 answer

476 views

can one define the pullback between stacks of coherent sheaves for non-flat morphisms?

asked Sep 1, 2011 at 10:32

3 votes

2 answers

1k views

if f is birational, is the pushforward map on the numerical groups surjective?

asked Oct 10, 2011 at 10:45

3 votes

1 answer

331 views

uniqueness of uniformizers

asked Oct 10, 2016 at 22:52

2 votes

1 answer

324 views

Is the pushforward via a proper map of a finite presentation module of finite presentation?

asked Mar 28, 2012 at 17:12

2 votes

1 answer

341 views

If tensor product has finite length, do higher Tors also have finite length?

asked Oct 4, 2016 at 16:58

2 votes

0 answers

253 views

Can I recognize the quotient of a group by a closed subgroup? (for example the standard representation of S3 in GL(2,C))

asked Aug 1, 2011 at 0:04

2 votes

1 answer

593 views

Does Hom(X,Spec R) = Hom(R, O(X)) hold for algebraic stacks?

asked Oct 29, 2011 at 22:08

1 vote

1 answer

245 views

If X -> Y -> X is the identity and Y is of finite type, can I say anything about X?

asked Sep 14, 2011 at 14:19

0 votes

0 answers

123 views

Books on algebraic groups over C with examples [duplicate]

asked Sep 27, 2017 at 14:29

Stack Exchange Network

21 Questions

how to make the category of chain complexes into an $\infty$-category

can a common mortal understand why the affine line is not smooth in brave new algebraic geometry?

what is the stringy Kähler moduli space?

coarse moduli space and $\pi_0$

Reference for the derived category of $X$, $[X/G]$ and $X/G$

surjective morphism of schemes or epimorphism of sheaves?

What is the negative cyclic homology of a smooth projective variety?

where to learn K-group of coherent sheaves modulo numerical equivalence?

Description of flop as graded algebra

Resolutions by free Differential Graded Algebras

Colimits in colimits of categories

If $f: X \to Y$ is a finite flat morphism of schemes, $g: Y \to Z$ is a proper morphism of relative dimension one, $Z$ is affine and $E$ is a vector bundle on $Y$ with $R^1g_E=0$ then $H^1(X,f^E)=0$?

can one define the pullback between stacks of coherent sheaves for non-flat morphisms?

if f is birational, is the pushforward map on the numerical groups surjective?

uniqueness of uniformizers

Is the pushforward via a proper map of a finite presentation module of finite presentation?

If tensor product has finite length, do higher Tors also have finite length?

Can I recognize the quotient of a group by a closed subgroup? (for example the standard representation of S3 in GL(2,C))

Does Hom(X,Spec R) = Hom(R, O(X)) hold for algebraic stacks?

If X -> Y -> X is the identity and Y is of finite type, can I say anything about X?

Books on algebraic groups over C with examples [duplicate]