Discrete Physics and the Dirac Equation
  We rewrite the 1+1 Dirac equation in light cone coordinates in two significant forms, and solve them exactly using the classical calculus of finite differences. The complex form yields ``Feynman's Checkerboard''---a weighted sum over lattice paths. The rational, real form can also be interpreted in terms of bit-strings. 
L. H. Kauffman (Univ. Illinois) and H. P. Noyes (SLAC)