User Allen Knutson

17 votes

What is significant about the half-sum of positive roots?

answered Nov 8, 2011 at 1:31

17 votes

Books you would like to see translated into English

answered Mar 11, 2010 at 2:48

17 votes

What are the worst notations, in your opinion?

answered Mar 19, 2010 at 5:59

17 votes

Understanding moment maps and Lie brackets

answered Feb 7, 2010 at 19:54

17 votes

A slick proof of the Bruhat Decomposition for GL_n(k)?

answered Feb 17, 2010 at 3:19

15 votes

Why do wedges of spheres often appear in combinatorics?

answered Mar 7, 2010 at 13:33

15 votes

Theorems with unexpected conclusions

answered Mar 14, 2010 at 2:38

15 votes

Exceptional isomorphisms of Lie groups

answered Nov 19, 2011 at 17:05

15 votes

On referee-author communications

answered Jan 2, 2011 at 22:26

15 votes

Recent, elementary results in algebraic geometry

answered Nov 4, 2014 at 12:12

15 votes

Quotients by the additive group $\mathbb G_a$

answered Aug 9, 2014 at 18:03

15 votes

Accepted

Partial (or complete) flag varieties as GIT quotients of affine spaces

answered Aug 21, 2013 at 5:03

14 votes

Accepted

Why does the degree of the variety of rank at most $r$ $n\times n$ matrices equal dim$S_{(n-r)^{n-r}}C^n$?

answered Sep 5, 2013 at 5:14

14 votes

Necessary and sufficient conditions for Littlewood Richardson coefficients to be non zero

answered Apr 29, 2014 at 21:56

14 votes

Varieties cut by quadrics

answered Jan 12, 2010 at 13:23

14 votes

Why do we care about the Hilbert scheme of points?

answered Sep 29, 2010 at 2:44

14 votes

Geometrical meaning of Grassmann algebra

answered Apr 27, 2010 at 1:29

13 votes

Really rigid varieties

answered Aug 3, 2011 at 21:34

13 votes

Topology of SU(3)

answered Jul 4, 2011 at 17:48

13 votes

Coefficients in cohomology

answered Apr 30, 2011 at 15:02

13 votes

What does the term "yoga" mean in mathematics?

answered May 6, 2011 at 1:55

13 votes

Is being reduced a generic property of schemes?

answered Jan 19, 2015 at 22:20

13 votes

Why there is a relation among the second-order minors of a symmetric $4\times 4$ matrix?

answered Jun 13, 2015 at 3:18

13 votes

Locked convex polyhedra

answered Jan 9, 2016 at 14:01

12 votes

Examples of theorems with proofs that have dramatically improved over time

answered Aug 28, 2016 at 20:40

12 votes

What are parabolic bundles good for?

answered Mar 8, 2016 at 3:36

12 votes

Accepted

Horn's inequalities for n matrices

answered Jul 29, 2014 at 16:07

12 votes

Who colored in my Dynkin diagrams?

answered Dec 13, 2010 at 18:10

12 votes

reference containing the list of irreducible finite dimensional representation of real general linear group

answered Mar 28, 2011 at 3:43

12 votes

What is Borel-de Siebenthal theory?

answered Jun 23, 2010 at 13:46

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276 Answers

What is significant about the half-sum of positive roots?

Books you would like to see translated into English

What are the worst notations, in your opinion?

Understanding moment maps and Lie brackets

A slick proof of the Bruhat Decomposition for GL_n(k)?

Why do wedges of spheres often appear in combinatorics?

Theorems with unexpected conclusions

Exceptional isomorphisms of Lie groups

On referee-author communications

Recent, elementary results in algebraic geometry

Quotients by the additive group $\mathbb G_a$

Partial (or complete) flag varieties as GIT quotients of affine spaces

Why does the degree of the variety of rank at most $r$ $n\times n$ matrices equal dim$S_{(n-r)^{n-r}}C^n$?

Necessary and sufficient conditions for Littlewood Richardson coefficients to be non zero

Varieties cut by quadrics

Why do we care about the Hilbert scheme of points?

Geometrical meaning of Grassmann algebra

Really rigid varieties

Topology of SU(3)

Coefficients in cohomology

What does the term "yoga" mean in mathematics?

Is being reduced a generic property of schemes?

Why there is a relation among the second-order minors of a symmetric $4\times 4$ matrix?

Locked convex polyhedra

Examples of theorems with proofs that have dramatically improved over time

What are parabolic bundles good for?

Horn's inequalities for n matrices

Who colored in my Dynkin diagrams?

reference containing the list of irreducible finite dimensional representation of real general linear group

What is Borel-de Siebenthal theory?