Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An existence theorem for the Cauchy problem on a characteristic cone for
  the Einstein equations   We prove an existence theorem for the Cauchy problem on a characteristic cone
for the vacuum Einstein equations.

29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
1
The categories of this paper are: cs
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg