Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Interpretation of the 'Extra' Variables in the Hurwitz
  Transformation   The Hurwits transformation is generalized by introducing three new variables
called 'extra'. Interpretation of these extra variables allows us to establish
relation between isotropic harmonic oscillator and five-dimensional
hydrogen-like atom in 'electromagnetic' fields of various configurations. For
the Schrodinger equations, the scheme of separation of extra variables is
suggested.

2
The categories of this paper are: math
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom