Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Crossed product of a C*-algebra by a semigroup of endomorphisms
  generated by partial isometries   The paper presents a construction of the crossed product of a C*-algebra by a
semigroup of endomorphisms generated by partial isometries.

15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio