Questions tagged [torus-action]
The torus-action tag has no usage guidance.
12
questions with no upvoted or accepted answers
11
votes
0
answers
249
views
Can the orbit with respect to a rotation on the torus hit an algebraic variety infinitely often?
Question: Does there exist a $d$-tuple $\alpha = (\alpha_1,\dots,\alpha_d) \in \mathbb{R}^d$ (with $1,\alpha_1, \dots,\alpha_d$ linearly independent over $\mathbb{Q}$) and an algebraic variety $V \...
- 1,762
8
votes
0
answers
279
views
Does Borel fixed-point theorem hold for Deligne-Mumford stacks?
Let $X$ be a proper Deligne-Mumford stack over $\mathbb{C}$ with an action by a complex torus $T$. Let $X^T$ denote the fixed locus.
Question: Is the following statement true?
...
7
votes
0
answers
374
views
The scheme-theoretic flow-in locus
Let $R$ be a ring with an $\mathbb{N}\times\mathbb{Z}$-grading. The $\mathbb{N}$-grading allows you to construct the scheme $X = \operatorname{Proj} R$, and the $\mathbb{Z}$-grading defines an action ...
- 2,527
4
votes
0
answers
132
views
Singular schemes with a torus action and embedded points
I've got a couple rather geometric questions about the following setup.
Let $X$ be a scheme over an algebraically closed field ($\mathbb{C}$, say) with the action of a torus $T$, such that the action ...
- 841
4
votes
0
answers
117
views
Twisting stable maps to C* equivariant space by a line bundle
Let $X$ be a $\mathbb{C}^*$-equivariant algebraic variety. Then there is a notion of a map to $X$ twisted by a line bundle. Namely, let $B$ be a variety and $L/B$ a line bundle. Let $P_L=L\setminus B$...
- 7,902
3
votes
0
answers
90
views
Decompositions from torus actions and compactness of (sub-)level sets
Let $T=\mathbb{C}^{*}$ act on a smooth complex quasi-projective variety $X$. Assume that the limit point $\lim_{t\to 0}t\cdot x$ exists for every $x\in X$.
From the induced $U(1)$-action and its (...
- 22.7k
2
votes
0
answers
170
views
Understanding the proof of a theorem by Van Den Bergh
I'm trying to understand the proof of a theorem by Van Den Bergh, which is Proposition 6 in the paper Bessenrodt, Christine and Lieven Le Bruyn. “Stable rationality of certain PGLn-quotients.” ...
- 767
2
votes
0
answers
169
views
Determining a toric GIT quotient
Consider the following $G = (\mathbb{C}^*)^{\times 3}$-action on $\mathbb{A}^6$:
$(\lambda_0,\lambda_1,\lambda_2) \cdot (x_0,x_1,x_2,y_0,y_1,y_2) = (\lambda_0x_0,\lambda_1x_1,\lambda_2x_2,\frac{\...
- 197
2
votes
0
answers
360
views
Are schematic fixed points of a torus action on an affinized twistor deformation flat?
This is a follow-up to some earlier questions about flatness of schematic fixed points of certain deformations. Since I could never come up with good enough hypotheses in those examples, let me try a ...
- 44k
1
vote
0
answers
84
views
How can I compute minimal distance of the AG-code on the Hirzebruch surface $\mathbb{F}_3$?
Let $\mathbb{F}_3$ be the Hirzebruch surface (with index $3$) over a finite field $\mathbb{F}_q$ and $\pi\!: \mathbb{F}_3 \to \mathbb{P}^1$ be the unique $\mathbb{P}^1$-fibration on $\mathbb{F}_3$. ...
- 1,801
0
votes
0
answers
145
views
Is $k$-diagonalizable element in split maximal torus of $G(k)$?
let $k$ be any field of char 0. $G$ is split reductive algebraic group over k. Let p in
G(k) be k-diagonalizable. Does there exist a split maximal torus of G(k) containing p?
I know that is ture for ...
0
votes
0
answers
437
views
Lifting of torus action to line bundle
Let $\mathbb{P}(V) = \mathbb{P}(\mathbb C \oplus \mathbb C)$ be with a $\mathbb C^*$ action : $\lambda (u,v) = (u,\lambda v)$.
There are two fixed points of this action, say $0$ and $\infty$. What ...
- 43