Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Conditional Symmetries and Riemann Invariants for Hyperbolic Systems of
  PDEs
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs