User Jim Humphreys

6 votes

0 answers

304 views

How to decide if two surfaces occurring in Springer theory are isomorphic?

asked Sep 25, 2011 at 22:53

6 votes

3 answers

993 views

Occurrences of a simple reflection in the longest element of a Weyl group?

asked Mar 20, 2011 at 22:12

6 votes

1 answer

749 views

Origin of symbols used for half-sum of positive roots in Lie theory?

asked Jan 19, 2014 at 16:26

6 votes

2 answers

1k views

Convention about "long" roots for simple Lie algebras of types ADE?

asked Jan 14, 2015 at 13:46

5 votes

1 answer

248 views

Vanishing of power of nilpotent operator $\mathrm{ad} \, \;e$ in different characteritics

asked May 1, 2016 at 20:04

5 votes

2 answers

1k views

Origin of notion of "split Grothendieck group"?

asked Jan 7, 2013 at 13:14

5 votes

0 answers

761 views

Applications (and source) of Bourbaki exercise on root systems with two root lengths?

asked Dec 22, 2010 at 23:26

5 votes

2 answers

439 views

Difference of adjacent dominant weights is a root?

asked Mar 29, 2018 at 23:30

4 votes

0 answers

472 views

Classify cross-sections of the adjoint quotient for a semisimple algebraic group?

asked Dec 29, 2012 at 19:21

4 votes

1 answer

713 views

Criterion for nilradical of a maximal parabolic subalgebra to be abelian?

asked Apr 28, 2013 at 22:47

3 votes

0 answers

209 views

What is known about 2-modular representations of Ree groups of type $F_4$?

asked Jan 24, 2013 at 23:22

3 votes

0 answers

182 views

Origin of the standard result on convex hull of weights of an irreducible finite dimensional representation?

asked Sep 10, 2019 at 23:03

2 votes

0 answers

256 views

Certain central extensions of simply connected simple algebraic groups

asked Jul 21, 2013 at 16:14

0 votes

1 answer

186 views

Absolute irreducibility of a symmetric square?

asked Aug 25, 2014 at 18:48

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74 Questions

How to decide if two surfaces occurring in Springer theory are isomorphic?

Occurrences of a simple reflection in the longest element of a Weyl group?

Origin of symbols used for half-sum of positive roots in Lie theory?

Convention about "long" roots for simple Lie algebras of types ADE?

Vanishing of power of nilpotent operator $\mathrm{ad} \, \;e$ in different characteritics

Origin of notion of "split Grothendieck group"?

Applications (and source) of Bourbaki exercise on root systems with two root lengths?

Difference of adjacent dominant weights is a root?

Classify cross-sections of the adjoint quotient for a semisimple algebraic group?

Criterion for nilradical of a maximal parabolic subalgebra to be abelian?

What is known about 2-modular representations of Ree groups of type $F_4$?

Origin of the standard result on convex hull of weights of an irreducible finite dimensional representation?

Certain central extensions of simply connected simple algebraic groups

Absolute irreducibility of a symmetric square?