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9h
comment From Weyl groups to Weyl groupoids?
@SaalHardali You can change what the accepted answer is.
22h
comment From Weyl groups to Weyl groupoids?
@user89334 Fair enough. Like I said, I wasn't really sure what the user wanted.
1d
answered From Weyl groups to Weyl groupoids?
1d
comment From Weyl groups to Weyl groupoids?
The isotropy group of a Cartan in your groupoid is not the Weyl group; you also get elements coming from diagram automorphisms. For $\mathfrak{sl}(n)$, minus transpose is an algebra automorphism preserving the usual Cartan, but doesn't come from an element of the Weyl group.
Apr
22
comment How fine an invariant of a representation is its quotient singularity?
@benblumsmith The preimage of the smooth locus is $V$ minus the fixed subspace for each individual group element. All of these have complex codimension $\geq 2$, since none of them are pseudoreflections, so removing them doesn't change the fundamental group.
Apr
21
revised If a faithfully flat extension of dg/A_$\infty$-algebra is formal, is the original algebra formal (over positive characteristic)?
added 173 characters in body
Apr
21
asked If a faithfully flat extension of dg/A_$\infty$-algebra is formal, is the original algebra formal (over positive characteristic)?
Apr
21
awarded  Nice Question
Apr
21
accepted What's known about the stalks of Lusztig's perverse sheaves on quiver varieties?
Apr
21
comment What's known about the stalks of Lusztig's perverse sheaves on quiver varieties?
That's a good point. I wish I could remember now what question I thought this would resolve.
Apr
15
comment Is Koszulity equivalent to the Lusztig character formula holding?
@ChrisBowman I think that only works in type A. I assume you want an arbitrary reductive algebraic group.
Apr
14
answered Is Koszulity equivalent to the Lusztig character formula holding?
Apr
4
comment Is the category of mixed Hodge modules bi-filtered?
But the associated graded for $F$ isn't a D-module, so it's obviously not a mixed Hodge module, right? Am I going crazy here?
Mar
26
answered How fine an invariant of a representation is its quotient singularity?
Mar
22
awarded  Nice Question
Mar
21
answered Understanding “Decategorified” symplectic Khovanov homology
Mar
20
comment Curves in homogeneous varieties
@JasonStarr That feels like reading in way too much thought to me. After all, the statement is obviously wrong as stated (since connectedness is not assumed).
Mar
20
answered Curves in homogeneous varieties
Mar
18
answered Independence of $\ell$ of Betti numbers
Mar
16
comment Borel--Bott--Weil for the Grassmannians
Yes. The theorem is exactly the same. The highest weights which appear are the ones that extend to characters of $P$. The proof is just pushing forward under the obvious map, and noting that those line bundles are trivial on the fibers.