Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Beyond Mumford's theorem on normal surfaces   Beyond normal surfaces there are several open questions concerning 2-
dimensional spaces. We present some results and conjectures along this line.

6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci