Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A note on QED gauge invariance of off-shell amplitudes
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg