Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Higher-Order Recursion Abstraction: How to Make Ackermann, Knuth and
  Conway Look Like a Bunch of Primitives, Figuratively Speaking
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex