  We discuss interacting fermion models in two dimensions, and, in particular,
such that can be solved exactly by bosonization. One solvable model of this
kind was proposed by Mattis as an effective description of fermions on a square
lattice. We review recent work on a specific relation between a variant of
Mattis' model and such a lattice fermion system, as well as the exact solution
of this model. The background for this work includes well-established results
for one-dimensional systems and the high-Tc problem. We also mention exactly
solvable extensions of Mattis' model.
