Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stability of spherically symmetric timelike thin-shells in general
  relativity with a variable equation of state   We study spherically symmetric timelike thin-shells in $3+1-$dimensional bulk
spacetime with a variable equation of state for the fluid presented on the
shell. In such a fluid the angular pressure $p$ is a function of both surface
energy density $\sigma $ and the radius $R$ of the thin-shell. Explicit cases
of the thin shells connecting two non-identical cloud of strings spacetimes and
a flat Minkowski spacetime to the Schwarzschild metric are investigated.

17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex