<A HREF="https://www.semanticscholar.org/paper/Another-solution-of-2D-Ising-model-Vergeles/32a4290b30c52ffe8df729a49394d06b9a582502">Another solution of 2D Ising model</A> (2009) [also at <A HREF="https://arxiv.org/abs/0805.0225">arXiv:0805.0225</A>]

> The partition function of the Ising model on a two-dimensional regular
> lattice is calculated by using the matrix representation of a Clifford
> algebra (the Dirac algebra), with number of generators equal to the
> number of lattice sites. It is shown that the partition function over
> all loops in a 2D lattice including self-intersecting ones is the
> trace of a polynomial in terms of Dirac matrices. The polynomial is an
> element of the rotation group in the spinor representation. Thus, the
> partition function is a function of a character on an orthogonal group
> of a high degree in the spinor representation.