Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Local structure theorem and equivariant geometry of cotangent
  bundles   Let $G$ be a connected reductive group acting on an irreducible normal
algebraic variety $X$. We give a slightly improved version of local structure
theorems obtained by F.Knop and D.A.Timashev that describe an action of some
parabolic subgroup of $G$ on an open subset of $X$. We also extend various
results of E.B.Vinberg and D.A.Timashev on the set of horospheres in $X$.
  We construct a family of nongeneric horospheres in $X$ and a variety $\Hor$
parameterizing this family, such that there is a rational $G$-equivariant
symplectic covering of cotangent vector bundles $T^*\Hor \dashrightarrow T^*X$.
As an application we get a description of the image of the moment map of $T^*X$
obtained by F.Knop by means of geometric methods that do not involve
differential operators.

20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
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The categories of this paper are: supr-con
29
The categories of this paper are: funct-an