Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generalised hyperbolicity in spacetimes with Lipschitz regularity   In this paper, we obtain general conditions under which the wave equation is
well-posed in spacetimes with metrics of Lipschitz regularity. In particular,
the results can be applied to spacetimes where there is a loss of regularity on
a hypersurface such as shell-crossing singularities, thin shells of matter and
surface layers. This provides a framework for regarding gravitational
singularities, not as obstructions to the world lines of point-particles, but
rather as an obstruction to the dynamics of test fields.

15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol