In section 3.2 of Kontsevich's very interesting paper ["Notes on motives in finite characteristic,"][1], he gives an axiomatic definition of a "lattice model" attached to a Boltzmann datum $(V_1,V_2,R)$, where $V_1$ and $V_2$ are vector spaces and $R$ is a linear endomorphism of $V_1$ tensor $V_2$.  He remarks that the 2-dimensional Ising model is an example.  Can someone explain to me what $V_1$, $V_2$, and $R$ are for the 2-dimensional Ising model?


  [1]: http://arxiv.org/PS_cache/math/pdf/0702/0702206v2.pdf