Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the local extension of Killing vector-fields in Ricci flat manifolds   We revisit the problem of extension of Killing vector-fields in smooth Ricci
flat manifolds, and its relevance to the black hole rigidity problem.

31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ