Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two Means of Compensating Fiber Nonlinearity Using Optical Phase
  Conjugation   Two fiber lines may compensate each other for nonlinearity with the help of
optical phase conjugation. The pair of fiber lines and the optical signals in
them may be either mirror-symmetric or translationally symmetric about the
conjugator.

24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas