Jim Humphreys's user avatar
Jim Humphreys's user avatar
Jim Humphreys's user avatar
Jim Humphreys
  • Member for 14 years, 1 month
  • Last seen more than 3 years ago
6 votes
0 answers
296 views

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

6 votes
3 answers
956 views

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

6 votes
1 answer
728 views

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

6 votes
2 answers
1k views

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

5 votes
1 answer
237 views

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

5 votes
2 answers
960 views

Origin of notion of "split Grothendieck group"?

5 votes
0 answers
729 views

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

5 votes
2 answers
418 views

Difference of adjacent dominant weights is a root?

4 votes
0 answers
465 views

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

4 votes
1 answer
669 views

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

3 votes
0 answers
209 views

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

3 votes
0 answers
156 views

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

2 votes
0 answers
251 views

Certain central extensions of simply connected simple algebraic groups

0 votes
1 answer
169 views

Absolute irreducibility of a symmetric square?

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