Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On exceptional sets of Hilbert transform   We prove several theorems concerning the exceptional sets of Hilbert
transform on the real line. In particular, it is proved that any null set is
exceptional set for the Hibert transform of an indicator function. The paper
also provides a real variable approach to the Kahane-Katsnelson theorem on
divergence of Fourier series.

3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con