Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Origin of the Universal Roughness Exponent of Brittle Fracture Surfaces:
  Correlated Percolation in the Damage Zone
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th