Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Cauchy problem for the wave equation with data on the boundary   We consider the Cauchy problem for the wave equation in $\Omega\times{\mathbb
R}$ with data given on some part of the boundary $\partial\Omega\times{\mathbb
R}$. We provide a reconstruction algorithm for this problem based on analytic
expressions. Our result is applicable to the problem of determining
nonstationary wave field arising in geophysics, photoacoustic tomography,
tsunami wave source recovery.

17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin