Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Non-Diagonal Singularity-Free Cosmological Perfect-Fluid Solution   We present a new non-diagonal G2 inhomogeneous perfect-fluid solution with
barotropic equation of state p=rho and positive density everywhere. It
satisfies the global hyperbolicity condition and has no curvature singularity
anywhere. This solution is very simple in form and has two arbitrary constants.

8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an