Parallelism and synchronization in two-level metacontrolled substitution grammars

Abstract A notion of synchronized substitution is introduced in the concept of two-level metacontrolled substitution grammar as defined in [6]. Whereas in [6] the top level is essentially grammar-independent, here the mechanism strongly depends on the grammars chosen. Furthermore we illustrate this mechanism on grammars which operate in parallel, namely E0L systems. Their language-generating power is compared with that of ET0L systems and E0L iterated systems.