Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A new proof of the $C^\infty$ regularity of $C^2$ conformal mappings on
  the Heisenberg group   We give a new proof for the $C^\infty$ regularity of $C^2$ smooth conformal
mappings of the sub-Riemannian Heisenberg group. Our proof avoids any use of
nonlinear potential theory and relies only on hypoellipticity of H\"ormander
operators and quasiconformal flows. This approach is inspired by prior work of
Sarvas and Liu.

33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph