Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Polarized HERA Collider   A brief review is given of the status of nucleon spin structure functions as
determined from polarized deep inelastic lepton-nucleon scatttering, including
current outstanding problems. The characteristics of a polarized HERA collider,
some of the particle physics topics it could address, and the accelerator
physics challenges it must meet are discussed.

32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas