Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Unidirectional Reflection and Invisibility in Nonlinear Media with an
  Incoherent Nonlinearity
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ