“…For understanding sub-exponential decay of correlation functions in dynamical systems, non-hyperbolic 1-dimensional maps have been studied by several authors [17,18,19,20,21,22,23,24,25,26] and they have found power law decay of correlations in their models. Therefore, it is natural to imagine connections of these non-hyperbolic maps and mixed type Hamiltonian systems, however, extensions of these maps to 2-dimensional area-preserving systems are unknown.…”