Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On Delusive Nodes of Free Oscillations   Two theorems and one conjecture about nodal sets of eigenfunctions arising in
various spectral problems for the Laplacian are reviewed. It occurred that all
these assertions are incorrect or only partly correct, but their analysis has
brought better understanding of the corresponding area of mathematical physics.
The contribution made by V. I. Arnold is emphasized.

15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn