Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superposition of a static perfect fluid and a radial elecric field   We obtain a two-parameter set of solutions, which represents a spherically
symmetric space-time with a superposition of a neutral fluid and an electric
field. The electromagnetic four-potential of this Einstein-Maxwell space-time
is taken in the form A=(q/n)(r^n)dt, when n=/0 and A=q*ln(r)dt, when n=0 (where
q and n are arbitrary constants)

21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an