Directed Percolation Universality in Asynchronous Evolution of Spatio-Temporal Intermittency

We present strong evidence that a coupled-map-lattice model for spatio-temporal intermittency belongs to the universality class of directed percolation when the updating rules are asynchronous, i.e. when only one randomly chosen site is evolved at each time step. In contrast, when the system is subjected to parallel updating, available numerical evidence suggests that it does not belong to this universality class and that it is not even universal. We argue that in the absence of periodic external forcing, the asynchronous rule is the more physical.