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awarded  Electorate
Jan
13
comment Can one describe the multiplication of two Bruhat cells?
I just mean that it's obvious from the rule that every cell that appears is gotten from $s_1\cdots s_mw_2$ by deleting some of the reflections. But you can't delete a totally arbitrary set of them; you can't delete one of if makes the product of the ones you've kept to the left times $w_2$ become longer, by the rule you cited. I was just too lazy to try to set up all the notation to write that out carefully, and apparently still am.
Jan
11
answered Can one describe the multiplication of two Bruhat cells?
Jan
10
comment Generators of pure braid groups of arbitrary Coxeter groups
It's hard to write the details since I have a baby in my other hand, but this is a fact we've used in more than one of our joint papers: any complexification of a real hyperplane arrangement has a presentation by loops around a single hyperplane.
Jan
8
revised Occurrence of the trivial representation in restrictions of Lie group representations
deleted 6 characters in body
Jan
8
awarded  Enlightened
Jan
8
awarded  Nice Answer
Jan
2
revised Is it worthwhile to give off-topic talks?
added 3 characters in body
Dec
28
revised Algorithm for finding the fewest cartesian products to partition a set of points
edited title
Dec
16
comment Is a quotient of a bound quiver algebra of finite representation type also representation-finite?
Every $A'$-module is an $A$-module by pullback, and this preserves non-isomorphism of modules. Thus, there are no more isomorphism types of indecomposable $A'$-modules than of $A$-modules.
Dec
15
reviewed No Action Needed Lorentzian vs Gaussian Fitting Functions
Dec
15
reviewed Leave Open A question regarding a fragment of Robinson Arithmetic
Dec
13
awarded  Nice Answer
Dec
10
reviewed Leave Open An almost periodic point must be a unifomly recurrent point?
Dec
10
reviewed Leave Open order of elements in a mapping space
Dec
10
reviewed Leave Open Generalized Euler characteristics of non-motivic origin
Dec
6
answered $U_q(\mathfrak{sl}_2)$ representations of “quantum dimension” zero
Dec
5
comment Description of the algebra of $G$-invariant polynomials by generators and relations
I'm totally confused; what are your generators $T_i$? Even if this presentation is right, it's extremely redundant: as Jason said, this is a hypersurface in $\mathbb{A}^3$ with the equation $uw=z^n$.
Dec
4
comment Pedagogical question on Lie groups vs. matrix Lie groups
It seems like any reasonable definition you make will ultimately be just "a quotient of a finite cover of a matrix group." In that context, it really is easier to define the exponential (just lift the path $\mathrm{exp}(tX)$), and the challenge of @DavidSpeyer is easy: do it for matrix groups and take a preimage, and then an image. It is all a little awkward, though.
Nov
28
comment The SGA1 version of Riemann's Existence Theorem is about analytic spaces. How does one relate it to topological covering spaces?
@nfdc23 Why is that first sentence (of your first comment) correct? It seems like that's the whole point of the question.