External versus Internal Hybridization for Cooperating Distributed Grammar Systems

Mitrana and PP aun commenced a study on cooperating distributed (CD) grammar systems with components working in diierent derivation modes, called hybrid CD grammar systems. In this paper, we introduce several hybrid derivation modes of CD grammar systems and characterize via this internal hybridization (i.e., all grammars of a CD grammar system work in the same mode) several external hy-bridizations (i.e., grammars of one CD grammar system may work in diierent modes) investigated by Mitrana and PP aun. When studying internal versus external hybridizations involving the so-called t-mode of derivation, we obtain cases when internally hybrid systems are strictly more respectively less powerful than their externally hybrid counterparts .