Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A Knapsack Intersection Hierarchy Applied to All-or-Nothing Flow in
  Trees
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th