User Qiaochu Yuan

7 votes

2 answers

1k views

Reference request: equivalence of formal group laws and Lie algebras in characteristic zero

asked Feb 12, 2011 at 21:55

7 votes

1 answer

533 views

Reference request: discrete harmonic functions and ends of graphs

asked Dec 22, 2010 at 2:39

7 votes

0 answers

249 views

Does there exist a commutative ring R such that SL_3(R) and SL_2(R) have the same finite subgroups?

asked Dec 3, 2010 at 15:52

7 votes

0 answers

330 views

What's the name of the cohomology class associated to a projective representation?

asked Nov 12, 2015 at 8:28

6 votes

1 answer

512 views

Fill in the blanks: "1Cob is the free category on a "

asked Feb 6, 2011 at 4:02

6 votes

3 answers

2k views

Is there a notation for the symmetric / antisymmetric subspaces of a tensor power that distinguishes them from the symmetric / exterior power?

asked Feb 7, 2011 at 21:26

6 votes

1 answer

2k views

When does a "representable functor" into a category other than Set preserve limits?

asked Apr 30, 2010 at 22:32

6 votes

4 answers

947 views

For a representation V of a finite group G, when is Hom(W, W⊗V) trivial for all irreps W?

asked Apr 25, 2010 at 19:53

6 votes

2 answers

695 views

Can the image of a Schur functor always be made an irreducible representation?

asked Jul 18, 2010 at 20:49

6 votes

3 answers

4k views

(How) should I take notes on a subject for self-study? [closed]

asked Oct 10, 2010 at 21:16

6 votes

1 answer

320 views

Is there a canonical notion of principal divisor on a discrete dynamical system?

asked Oct 21, 2009 at 4:13

6 votes

1 answer

578 views

Does there exist a sequence of groups whose representation theory is described by plane partitions?

asked Oct 16, 2009 at 16:39

5 votes

1 answer

449 views

Does this problem have a name? [Ducci Sequences]

asked Mar 8, 2010 at 1:10

5 votes

0 answers

304 views

Are these notions of group object with weak inverses equivalent?

asked Jun 1, 2011 at 17:12

5 votes

1 answer

513 views

Morita equivalence of acyclic categories

asked Jan 20, 2012 at 6:50

5 votes

0 answers

281 views

Is the "Toeplitz algebra" the representation ring of a Hopf algebra related to SU(2)?

asked Jun 28, 2012 at 12:43

5 votes

1 answer

648 views

Can we prove that there are countably many isomorphism classes of compact Lie groups without the classification of simple Lie algebras?

asked Jun 28, 2013 at 20:58

5 votes

1 answer

428 views

Centralizers in the universal central extensions of the alternating groups?

asked Feb 10, 2015 at 6:38

4 votes

1 answer

237 views

Reference request: "unoriented composition" in generalized categories

asked Feb 6, 2014 at 22:56

4 votes

5 answers

816 views

Does this kind of endofunctor ever have an initial algebra?

asked Apr 23, 2013 at 6:04

4 votes

1 answer

464 views

Examples of "inner products" of parallel morphisms in a dagger category

asked Aug 10, 2011 at 19:15

4 votes

1 answer

1k views

What is the abstract relationship between an indecomposable representation and a sum of irreducible representations with the same character?

asked Apr 5, 2010 at 20:55

3 votes

0 answers

209 views

How linearly independent are the obvious combinatorial invariants of a Bruhat interval?

asked Jul 21, 2010 at 19:36

3 votes

7 answers

1k views

What is the "right" definition of the free abelian group on a set?

asked Nov 22, 2009 at 23:04

3 votes

2 answers

885 views

Is the "diagonal" of a regular language always context-free?

asked Oct 15, 2009 at 4:44

3 votes

0 answers

247 views

Invariants of groups that are invariant under passage to finite index subgroups

asked Feb 4, 2014 at 2:15

2 votes

1 answer

557 views

What's the relationship between B Aut(G) and B Aut(BG) for a (discrete) group G?

asked Jan 31, 2014 at 1:46

2 votes

2 answers

400 views

Can the objects of every concrete category themselves be realized as small categories?

asked Oct 19, 2009 at 6:11

2 votes

2 answers

892 views

Is the existence of a well-ordering on R independent of ZF?

asked Nov 11, 2009 at 22:48

Stack Exchange Network

179 Questions

Reference request: equivalence of formal group laws and Lie algebras in characteristic zero

Reference request: discrete harmonic functions and ends of graphs

Does there exist a commutative ring R such that SL_3(R) and SL_2(R) have the same finite subgroups?

What's the name of the cohomology class associated to a projective representation?

Fill in the blanks: "1Cob is the free category on a "

Is there a notation for the symmetric / antisymmetric subspaces of a tensor power that distinguishes them from the symmetric / exterior power?

When does a "representable functor" into a category other than Set preserve limits?

For a representation V of a finite group G, when is Hom(W, W⊗V) trivial for all irreps W?

Can the image of a Schur functor always be made an irreducible representation?

(How) should I take notes on a subject for self-study? [closed]

Is there a canonical notion of principal divisor on a discrete dynamical system?

Does there exist a sequence of groups whose representation theory is described by plane partitions?

Does this problem have a name? [Ducci Sequences]

Are these notions of group object with weak inverses equivalent?

Morita equivalence of acyclic categories

Is the "Toeplitz algebra" the representation ring of a Hopf algebra related to SU(2)?

Can we prove that there are countably many isomorphism classes of compact Lie groups without the classification of simple Lie algebras?

Centralizers in the universal central extensions of the alternating groups?

Reference request: "unoriented composition" in generalized categories

Does this kind of endofunctor ever have an initial algebra?

Examples of "inner products" of parallel morphisms in a dagger category

What is the abstract relationship between an indecomposable representation and a sum of irreducible representations with the same character?

How linearly independent are the obvious combinatorial invariants of a Bruhat interval?

What is the "right" definition of the free abelian group on a set?

Is the "diagonal" of a regular language always context-free?

Invariants of groups that are invariant under passage to finite index subgroups

What's the relationship between B Aut(G) and B Aut(BG) for a (discrete) group G?

Can the objects of every concrete category themselves be realized as small categories?

Is the existence of a well-ordering on R independent of ZF?