Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three Problems of "Distinction"   Three problems related to the longest chains in an equivalence relation are
formulated. Their relevance in estimating the cardinal of quotient spaces, and
in particular, of reduced powers and ultrapowers, is indicated.

37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat