Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Sturm Liouville theorem for quadratic operator pencils   We establish a Sturm{Liouville theorem for quadratic operator pencils
counting their unstable real roots, with applications to stability of waves.
Such pencils arise, for example, in reduction of eigenvalue systems to
higher-order scalar problems.

36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph