Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Characteristic analysis for integrable soliton models on two-dimensional
  target spaces   We investigate the evolutionary aspects of some integrable soliton models
whose Lagrangians are derived from the pullback of a volume-form to a
two-dimensional target space. These models are known to have infinitely many
conserved quantities and support various types of exact analytic solutions with
nontrivial topology. In particular, we show that, in spite of the fact that
they admit nice smooth solutions, wave propagation about these solutions will
always be ill-posed. This is related to the fact that the corresponding
Euler-Lagrange equations are not of hyperbolic type.

18
The categories of this paper are: econ
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph