Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Space-time models derived from Schwarzschild's solution   We discuss two space-time models: one is expanding, the other is static. They
are both derived from Schwarzschild's exterior solution. But they differ in the
implementation of the parallelism at a distance and the choice of their master
frame of reference.

14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin