Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The $s$-polyharmonic extension problem and higher-order fractional
  Laplacians   We provide a detailed description of the relationships between the fractional
Laplacian of order $2s\in(0,n)$ on $\mathbb{R}^n$ and the
$\textit{$s$-polyharmonic}$ extension operator to the upper half space
$\mathbb{R}^{n+1}_+$.

6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
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The categories of this paper are: hep-th
1
The categories of this paper are: cs
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio