Synchronization and control in intrinsic and designed computation: An information-theoretic analysis of competing models of stochastic computation

We adapt tools from information theory to analyze how an observer comes to synchronize with the hidden states of a finitary, stationary stochastic process. We show that synchronization is determined by both the process's internal organization and by an observer's model of it. We analyze these components using the convergence of state-block and block-state entropies, comparing them to the previously known convergence properties of the Shannon block entropy. Along the way we introduce a hierarchy of information quantifiers as derivatives and integrals of these entropies, which parallels a similar hierarchy introduced for block entropy. We also draw out the duality between synchronization properties and a process's controllability. These tools lead to a new classification of a process's alternative representations in terms of minimality, synchronizability, and unifilarity. (C) 2010 American Institute of Physics. [doi:10.1063/1.3489888]