Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Revisiting the combinatorics of the 2D Ising model   We provide a concise exposition with original proofs of combinatorial
formulas for the 2D Ising model partition function, multi-point fermionic
observables, spin and energy density correlations, for general graphs and
interaction constants, using the language of Kac-Ward matrices. We also give a
brief account of the relations between various alternative formalisms which
have been used in the combinatorial study of the planar Ising model: dimers and
Grassmann variables, spin and disorder operators, and, more recently,
s-holomorphic observables. In addition, we point out that these formulas can be
extended to the double-Ising model, defined as a pointwise product of two Ising
spin configurations on the same discrete domain, coupled along the boundary.

25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int