Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Initial boundary-value problem for the spherically symmetric Einstein
  equations with fluids with tangential pressure
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
14
The categories of this paper are: math-ph