Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cylindrically Symmetric, Static, Perfect-Fluid Solutions of Einstein's
  Field Equations   Perfect-fluid, static, cylindrically symmetric solutions of Einstein's field
equations are obtained for the equations of state $\rho+3p=0$ and $\rho=p$. In
the former case, the density and the pressure turn out to be constant while in
the later case, they depend on the radial parameter $r$. Evan's solution
corresponding to the equation of state $\rho=p$ is included in the solutions
discussed here.

17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph