Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: HNN Extensions of von Neumann Algebras   Reduced HNN extensions of von Neumann algebras (as well as $C^*$-algebras)
will be introduced, and their modular theory, factoriality and ultraproducts
will be discussed. In several concrete settings, detailed analysis on them will
be also carried out.

15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics