  We consider by means of Monte Carlo simulations the relaxation in the
paramagnetic phase of the anti-ferromagnetic Ising model on a triangular
lattice and of a fully-frustrated Ising model on a square lattice. In
contradistinction to previous studies of the second model, we show that
spin-spin correlation functions do not decay with a stretched-exponential law
at low temperature but that both models display an exponential decay with
logarithmic corrections that are interpreted as the signature of topological
defects.
