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1 vote
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156 views

Software for computing invariant rings

I have an linearly reductive algebraic group $G$ acting regularly on an affine variety $X$(over an algebraically closed field of characteristic 0). I want to compute the invariant ring $\mathbb{K}[X]^{...
It'sMe's user avatar
  • 839
4 votes
0 answers
119 views

Invariants and subgroups

Let $G$ be an affine algebraic group over some algebraically closed field $K$, and let $H$ be a closed subgroup. Assume that $G$ acts algebraically on an affine variety $X$. Assume that $X'\subseteq ...
Ehud Meir's user avatar
  • 5,039
1 vote
0 answers
151 views

Generators of the same degree in a graded ring and GIT quotient

Let $S$ be a graded ring i.e. $S_d\cdot S_e \subset S_{d+e}$ where $S_d$ is the degree $d$ part of $S$. Assume $S_{<0}$ vanishes. For simplicity, you may think of $S$ as a graded subring of $\...
Hang's user avatar
  • 2,789
3 votes
1 answer
619 views

When is an almost geometric quotient flat?

All varieties here are over $\Bbb C$. Let $G$ be a reductive algebraic group acting algebraically on affine $n$-space $\Bbb A^n$. Let $R$ be the coordinate ring of $\Bbb A^n$. Assume that the natural ...
Avi Steiner's user avatar
  • 3,079