Cohen and Grossberg neural networks Strang–Marchuk splitting approach Wasserstein distance arithmetic progressions asymptotic distribution birth-death process bounds breakdown and repair busy period catastrophes continuous-time Markov chains differential entropy diffusion diffusion model discrete time stochastic model double-ended queues exact asymptotics exogenous factors first Chebyshev function first passage time (FPT) first-passage time first-passage-time forecast combinations fractional birth-death processes fractional differential-difference equations fractional queues fusion estimation general bulk service growth curves host-parasite interaction