  Using a Monte Carlo coarse-graining technique introduced by Binder et al., we
have explicitly constructed the continuum field theory for the zero-temperature
triangular Ising antiferromagnet. We verify the conjecture that this is a
gaussian theory of the height variable in the interface representation of the
spin model. We also measure the height-height correlation function and deduce
the stiffness constant. In addition, we investigate the nature of defect-defect
interactions at finite temperatures, and find that the two-dimensional Coulomb
gas scenario applies at low temperatures.
