Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A bijection between phylogenetic trees and plane oriented recursive
  trees   Phylogenetic trees are binary nonplanar trees with labelled leaves, and plane
oriented recursive trees are planar trees with an increasing labelling. Both
families are enumerated by double factorials. A bijection is constructed, using
the respective representations a 2-partitions and trapezoidal words.

33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph