Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On a frequency function approach to the unique continuation principle   In this survey we discuss the frequency function method so as to study the
problem of unique continuation for elliptic partial differential equations. The
methods used in the note were mainly introduced by Garofalo and Lin.

20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs