Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kropina metrics and Zermelo navigation on Riemannian manifolds   The present paper studies globally defined Kropina metrics as solutions of
the Zermelo's navigation problem. Moreover, we characterize the Kropina metrics
of constant flag curvature showing that up to local isometry, there are only
two model spaces of them: the Euclidean space and the odd-dimensional spheres.

6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn