Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three-coloring triangle-free graphs on surfaces VI. 3-colorability of
  quadrangulations   We give a linear-time algorithm to decide 3-colorability (and find a
3-coloring, if it exists) of quadrangulations of a fixed surface. The algorithm
also allows to prescribe the coloring for a bounded number of vertices.

24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio