  We study the one-dimensional projection of the extremal Gibbs measures of the
two-dimensional Ising model, the "Schonmann projection". These measures are
known to be non-Gibbsian at low temperatures, since their conditional
probabilities as a function of the two-sided boundary conditions are not
continuous. We prove that they are g-measures, which means that their
conditional probabilities have a continuous dependence on one-sided boundary
condition.
