Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: On the Riemann Extension of the G\"odel Space-Time metric   Some properties of the G\"odel space-time metric and its Riemann extension
are studied

0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
16
The categories of this paper are: stat