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Linear representations of algebras and groups, Lie theory, associative algebras, multilinear algebra.
7
votes
1
answer
399
views
Equality of codimension under Lusztig-Spaltenstein induction
Pardon if this is well known. Suppose I have a (say complex) connected reductive group $G^{\vee}$ with the $\tilde{\Delta}=\Delta\cup\{\alpha_0\}$ being the simple roots plus the negative highest root …
2
votes
0
answers
150
views
Definition 2.3 in Lusztig's "Character Sheaves I"
About Definition 2.3 in Character Sheaves I: We have the usual $G$, $B$, $T$, Weyl group $W$ and roots $R$. Lusztig wrote down a definition of $R_{\mathcal{L}}$ as:
$$R_{\mathcal{L}}=\{\alpha\in R\;|\ …
7
votes
2
answers
599
views
Relation between unipotent cuspidal representations and cuspidal local systems
This could well be a question for reading suggestion. Hope it's not too bad and thanks a lot.
So the question is as in the title. What are the relations between the notion of unipotent cuspidal repre …
5
votes
0
answers
45
views
Application of character sheaves to characters of $G(\mathbb{F}_q)$
I wish to ask about good examples of new applications of Lusztig's theory of character sheaves (and subsequent development, but excluding generalized Springer theory) back to the theory of characters …
5
votes
2
answers
323
views
Cartan subspaces for general algebraic representations
So I feel like asking the following likely open-ended question: What good generalizations of the notion of Cartan subspace do we have?
To be precise, let $G\curvearrowright V$ be an algebraic represe …
3
votes
0
answers
218
views
Shalika germ for local function field
I am wondering if there is a theorem of Shalika germ (as below) for local function field, for both the group version or the Lie algebra version, probably under assumption on the characteristic to be v …
3
votes
2
answers
607
views
counting points on nilpotent Springer fiber
Computing $p$-adic orbital integral I come to the following question. My ground field $k$ is the residue field of a non-arch local field, i.e. a finite field. I am happy to put any assumption on $\tex …
4
votes
0
answers
503
views
Parahorics and their normalizers
Let $G$ be a reductive group over a local non-arch field $F$. For convenience let's assume $G$ has anisotropic center (or even that $G$ is semisimple if preferred). Let $x$ be any point in the buildin …
4
votes
0
answers
280
views
Computing Springer action on the homology of affine Springer fibers
Lusztig defined (in Sec. 5, also Sage) a Springer action of the affine Weyl group on the homology of affine Springer fibers (Iwahori one, i.e. in an affine flag variety). In the regular semisimple unr …
5
votes
1
answer
215
views
About generalized Springer theory for spin groups
I am interested in the detailed computation of the generalized Springer theory for spin groups (type B or D). In the last sentence in Section 14 of Lusztig's Intersection cohomology complex on a reduc …
2
votes
1
answer
255
views
semisimple support of character sheaves
So the essential question is:
How should we think about, or if possible compute, the semisimple
support of a cuspidal character sheaf?
For example, let $G=SL_2$. We have the cuspidal characte …
2
votes
0
answers
140
views
Iwahori subalgebra as maximal solvable
I think the following is true, but haven't came up with a proof myself. Thanks in advance!
Let $G$ be a semisimple (to avoid more words) algebraic group over $\mathbb{C}$. Write $F=\mathbb{C}((t))$ a …
6
votes
0
answers
322
views
Counting points on Hessenberg varieties over a finite field
Let $G$ be an connected reductive group over finite field $k$. I will assume that $\text{char}(k)$ is very good for $G$ (or even larger, if preferred). Let $B\subset G$ be a Borel subgroup defined ove …
8
votes
0
answers
265
views
A Lie-theoretic question regarding $B\ltimes \mathfrak{g}/\mathfrak{b}$
I am stuck on a seeming elementary Lie-theoretic question arising from a study of components of affine Springer fibers. Will be very grateful if somebody would like to share some insight, or intereste …
4
votes
1
answer
162
views
A specific $2$-dimensional Galois representation of $G_{\mathbb{Q}_2}$ and its Langlands cor...
I am interested in understanding a situation in (classical, not $p$-adic) local Langlands for $\mathrm{GL}_p(\mathbb{Q}_p)$. An example of
it is as follows: Let $F=\mathbb{Q}_2$ and $E$ be the splitti …