Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Non-unital $C^{*}$-categories, (co)limits, crossed products and
  exactness
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg