Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Causal hierarchy of spacetimes, temporal functions and smoothness of
  Geroch's splitting. A revision   After the heroic epoch of Causality Theory, problems concerning the
smoothability of time functions and Cauchy hypersurfaces remained as unanswered
folk questions. Just recently solved, our aim is to discuss the state of the
art on this topic, including self-contained proofs for questions on causally
continuous, stably causal and globally hyperbolic spacetimes.

27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
3
The categories of this paper are: physics
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat