Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Defect lines, dualities, and generalised orbifolds   Defects are a useful tool in the study of quantum field theories. This is
illustrated in the example of two-dimensional conformal field theories. We
describe how defect lines and their junction points appear in the description
of symmetries and order-disorder dualities, as well as in the orbifold
construction and a generalisation thereof that covers exceptional modular
invariants.

1
The categories of this paper are: cs
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex