Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On topological restrictions of the spacetime in cosmology   In this paper we discuss the restrictions of the spacetime for the standard
model of cosmology by using results of the differential topology of 3- and
4-manifolds. The smoothness of the cosmic evolution is the strongest
restriction. The Poincare model (dodecaeder model), the Picard horn and the
3-torus are ruled out by the restrictions but a sum of two Poincare spheres is
allowed.

10
The categories of this paper are: q-bio
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ