Search Results
| Search type | Search syntax |
|---|---|
| Tags | [tag] |
| Exact | "words here" |
| Author |
user:1234 user:me (yours) |
| Score |
score:3 (3+) score:0 (none) |
| Answers |
answers:3 (3+) answers:0 (none) isaccepted:yes hasaccepted:no inquestion:1234 |
| Views | views:250 |
| Code | code:"if (foo != bar)" |
| Sections |
title:apples body:"apples oranges" |
| URL | url:"*.example.com" |
| Saves | in:saves |
| Status |
closed:yes duplicate:no migrated:no wiki:no |
| Types |
is:question is:answer |
| Exclude |
-[tag] -apples |
| For more details on advanced search visit our help page | |
Results tagged with ag.algebraic-geometry
Search options not deleted
user 4149
Algebraic varieties, stacks, sheaves, schemes, moduli spaces, complex geometry, quantum cohomology.
11
votes
Accepted
Galois action on Borovoi's algebraic fundamental group
$\newcommand{\sss}{{\rm ss}}
\newcommand{\ssc}{{\rm sc}}
\newcommand{\tor}{{\rm tor}}
\newcommand{\X}{{\sf X}}
\newcommand{\Q}{{\mathbb Q}}
\newcommand{\qed}{{$\blacksquare$}}
$Let $G$ be a (connected …
- 14.2k
8
votes
Central isogeny, Shimura varieties and exceptional cases
You can find answers to your questions in: Deligne, Pierre:
Variétés de Shimura: interprétation modulaire, et techniques de construction de modèles canoniques. Automorphic forms, representations and L …
- 14.2k
2
votes
Accepted
Regular embeddings of a reductive groups with induced center
The answer is Yes.
Let $G\hookrightarrow G'$ be a smooth regular embedding. We write $Z'=Z(G')$ for the center of $G'$, which is an $F$-torus where $F={\Bbb F}_q$.
We construct a regular embedding $G' …
- 14.2k
4
votes
Accepted
What is the minimum possible k-rank of a quasi-split reductive group over a field?
$\DeclareMathOperator\Gal{Gal}\DeclareMathOperator\im{im}\DeclareMathOperator\Aut{Aut}\DeclareMathOperator\SL{SL}$I add details to Friedrich's comment:
The question easily reduces to the case of a sem …
- 12.9k
6
votes
1
answer
264
views
Classification of algebraic groups of the types $^1\! A_{n-1}$ and $^2\! A_{n-1}$
This seemingly elementary question was asked in Mathematics StackExchange.com: https://math.stackexchange.com/q/4779592/37763.
It got upvotes, but no answers or comments, and so I ask it here.
Let $G$ …
- 6,614
2
votes
Accepted
Subgroups of $\operatorname{PGL}_n$
$\renewcommand{\O}{{\rm O}}
\newcommand{\GO}{{\rm GO}}
\newcommand{\PO}{{\rm PO}}
\newcommand{\PGO}{{\rm PGO}}
\newcommand{\GL}{{\rm GL}}
\newcommand{\PGL}{{\rm PGL}}
\newcommand{\SL}{{\rm SL}}
\new …
- 12.9k
6
votes
2
answers
366
views
Twisted forms with real points of a real Grassmannian
Let $X={\rm Gr}_{n,k,{\Bbb R}}$ denote the Grassmannian of $k$-dimensional subspaces in ${\Bbb R}^n$.
We regard $X$ as an ${\Bbb R}$-variety with the set of complex points $X({\Bbb C})={\rm Gr}_{n,k,{ …
- 15.5k
3
votes
0
answers
123
views
Obstruction to the existence of a deformation of a subvariety compatible with the given defo...
Let $X$ be a smooth projective variety over a field $k$ of characteristic 0,
and let $A$ be a local Artinian $k$-algebra, say, $A=k\oplus I$
where $I$ is an ideal such that $I^2=0$.
Let $\frak X$ be a …
- 14.2k
7
votes
1
answer
477
views
Conjugation of the quotient of $\mathrm{SL}(n,\mathbb{C})$ by a finite subgroup
$\DeclareMathOperator\SL{SL}\DeclareMathOperator\Aut{Aut}$EDITED Let $G=\SL_{n,{\mathbb{C}}}$, the special linear group over ${\mathbb{C}}$.
Let $H\subset G$ be a finite subgroup.
Set $X=G/H$ be the c …
- 2,368
3
votes
1
answer
233
views
Is Deligne's braiding functorial?
$\newcommand{\ssc}{{\rm sc}}
\newcommand{\ad}{{\rm ad}}
\newcommand{\Fbar}{{\overline F}}
$
Let $F$ be a field and $\Fbar$ be a fixed algebraic closure of $F$.
Let $G$ be a (connected) reductive group …
- 14.2k
2
votes
Is Deligne's braiding functorial?
$\newcommand{\ssc}{{\rm sc}}
\newcommand{\sss}{{\rm ss}}
\newcommand{\ad}{{\rm ad}}
\newcommand{\wh}{\widehat}
\newcommand{\wt}{\widetilde}
\newcommand{\pitil}{\tilde\pi}
\newcommand{\rhotil}{\tilde\r …
- 14.2k
4
votes
0
answers
197
views
Non-trivial example of a variety with an action of a unipotent group?
$
\renewcommand{\C}{{\mathbb C}}
\renewcommand{\R}{{\mathbb R}}
$
In the preprint Taking quotient by a unipotent group induces a homotopy equivalence
we proved the following result:
Theorem.
Let $U$ …
- 14.2k
2
votes
density in SU(2,1)
(EDITED taking in account the comment of Yves.) The group denoted in the question by $SU(2,1)(K)$ is the group of $\mathbf{Q}$-points $G(\mathbf{Q})$ for a suitable $\mathbf{Q}$-group $G$, and the gro …
- 14.2k
12
votes
Are units of rings of functions on algebraic varieties finitely generated (mod. constants)?
I translate into English Lemma 6.5 from Sansuc's paper Groupe de Brauer et arithmétique des groupes
algébriques linéaires sur un corps de nombres, J. reine angew. Math.
327 (1981), 12-80.
Let $X$ be …
- 14.2k
4
votes
Accepted
Bounds on Tamagawa numbers of reductive groups
Yes, the formula is correct, see Sansuc, J.-J. Groupe de Brauer et arithmétique des groupes algébriques linéaires sur un corps de nombres. J. Reine Angew. Math. 327 (1981), 12–80, (10.1.2).
In the ext …
- 14.2k