Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Variations on a theme of Kasteleyn, with application to the totally
  nonnegative Grassmannian   We provide a short proof of a classical result of Kasteleyn, and prove
several variants thereof. One of these results has become key in the
parametrization of positroid varieties, and thus deserves the short direct
proof which we provide.

17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys