Comment on ‘‘Stochastic pathway to anomalous diffusion’’

A continuous-time random walk with a coupled space and time dependence of the waiting-time distribution recently introduced by Klafter, Blumen, and Shlesinger Phys. Rev. A 35, 3081 (1987) is reconsidered. A simple probabilistic analysis of the problem is presented, and the diffusion behavior in one of the four possible regimes is found to differ from the prediction of Klafter, Blumen, and Shlesinger.