Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Properties of Exact Solutions Endowed with Negative Mass   It is shown that various pathological properties of spacetimes can be
explained by the presence of negative mass, including the cases when the total
mass of the solution is a positive quantity. As an illustration, we consider
several well-known stationary axisymmetric vacuum and electrovac solutions of
the Einstein-Maxwell equations. Our investigation naturally leads to a critique
of the known maximal extensions of the Kerr and Kerr-Newman spacetimes which
turn out to be neither analytic nor physically meaningful.

12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th