Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reduction of the gravitational lens equation to a one-dimensional
  non-linear form for the tilted Plummer model family   The gravitational lens equation for the tilted Plummer family of models can
be reduced to a one-dimensional non-linear equation. For certain values of the
slope of the radial profile it can be reduced to a polynomial form. Both forms
are advantageous to find the roots, i.e. the images for a given model. The
critical curve equations can also be reduced to a non-linear or polynomial
form, and therefore it is useful to find the caustics. This lens model family
has ample use in gravitational lens theory, and can produce up to five images.

2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con