Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Collaborative thesaurus tagging the Wikipedia way   This paper explores the system of categories that is used to classify
articles in Wikipedia. It is compared to collaborative tagging systems like
del.icio.us and to hierarchical classification like the Dewey Decimal
Classification (DDC). Specifics and commonalitiess of these systems of subject
indexing are exposed. Analysis of structural and statistical properties
(descriptors per record, records per descriptor, descriptor levels) shows that
the category system of Wikimedia is a thesaurus that combines collaborative
tagging and hierarchical subject indexing in a special way.

28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas