Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Classical Integrability of Two Dimensional Non Linear Sigma Models   The conditions under which a general two-dimensional non-linear sigma model
is classically integrable are given. These requirements are found by demanding
that the equations of motion of the theory are expressible as a zero curvature
relation. Some new integrable two-dimensional sigma models are then presented.

29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
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
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ