Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Projective Geometry and $\cal PT$-Symmetric Dirac Hamiltonian
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg