Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The # product in combinatorial Hopf algebras   We show that the # product of binary trees introduced by Aval and Viennot
[arXiv:0912.0798] is in fact defined at the level of the free associative
algebra, and can be extended to most of the classical combinatorial Hopf
algebras.

32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph