Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On geodesic flows with symmetries and closed magnetic geodesics on
  orbifolds   Let $Q$ be a closed manifold admitting a locally-free action of a compact Lie
group $G$. In this paper we study the properties of geodesic flows on $Q$ given
by Riemannian metrics which are invariant by such an action. In particular, we
will be interested in the existence of geodesics which are closed up to the
action of some element in the group $G$, since they project to closed magnetic
geodesics on the quotient orbifold $Q/G$.

29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol