Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Optimal preconditioning for the symmetric and non-symmetric coupling of
  adaptive finite elements and boundary elements
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an