Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the equivariant reduction of structure group of a principal bundle to
  a Levi subgroup   Let $M$ be an irreducible projective variety over an algebraically closed
field $k$ of characteristic zero equipped with an action of a group $\Gamma$.
Let $E_G$ be a principal $G$--bundle over $M$, where $G$ is a connected
reductive algebraic group over $k$, equipped with a lift of the action of
$\Gamma$ on $M$. We give conditions for $E_G$ to admit a $\Gamma$--equivariant
reduction of structure group to $H$, where $H \subset G$ is a Levi subgroup. We
show that for $E_G$, there is a naturally associated conjugacy class of Levi
subgroups of $G$. Given a Levi subgroup $H$ in this conjugacy class, $E_G$
admits a $\Gamma$--equivariant reduction of structure group to $H$, and
furthermore, such a reduction is unique up to an automorphism of $E_G$ that
commutes with the action of $\Gamma$.

17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom