Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Instance optimal Crouzeix-Raviart adaptive finite element methods for
  the Poisson and Stokes problems
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg