Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Inverse scattering for the 1-D Helmholtz equation   We prove a uniqueness result for Nevanlinna functions. and this result is
then used to give an elementary proof of the uniqueness in the inverse
scattering problem for the equation $ u" + \frac{k^2}{c^2}u=0 $ on $\mathbb R$.
Here $c$ is a real positive measurable function that is bounded from below by a
positive constant, and is close to $1$ at $\pm \infty$.

24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics