Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Smooth solutions and singularity formation for the inhomogeneous
  nonlinear wave equation   We study the nonlinear inhomogeneous wave equation in one space dimension:
$v_{tt} - T(v,x)_{xx} = 0$. By constructing some "decoupled" Riccati type
equations for smooth solutions, we provide a singularity formation result
without restrictions on the total variation of unknown, which generalize
earlier singularity results of Lax and the first author. These results are
applied to several one-dimensional hyperbolic models, such as compressible
Euler flows with a general pressure law, elasticity in an inhomogeneous medium,
transverse MHD flow, and compressible flow in a variable area duct.

1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph