On the number of components in cooperating distributed grammar systems

AbstractIt is proved that the number of components in context-free cooperating distributed (CD) grammar systems can be reduced to 3 when they are working in the so-called sf-mode of derivation, which is the cooperation protocol which has been considered first for CD grammar systems. In this derivation mode, a component continues the derivation until and unless there is a nonterminal in the sentential form which cannot be rewritten according to that component. Moreover, it is shown that CD grammar systems in sf-mode with only one component can generate only the context-free languages but they can generate non-context-free languages if two components are used. The sf-mode of derivation is compared with other well-known cooperation protocols with respect to the hierarchies induced by the number of components

Systems of Parallel Grammars

Tato práce definuje kooperující distribuované gramatické systémy založené na E0L systémech namísto bezkontextových gramatik. Zkoumá jejich generativní sílu především vzhledem k ET0L systémům. Připomíná hlavní závěry o CD GS, následně definuje upravené systémy a poskytuje důkazy o síle jednotlivých jejich derivačních módů. Většina módů se silou rovná ET0L systémům, s výjimkou ukončovacího módu, pro který je poskytnut důkaz o větší síle. Prezentováno je několik vysvětlených příkladů nových systémů.This article defines cooperating distributed grammar systems with E0L components instead of context-free grammars and discusses its generative power mainly in respect to ET0L systems. It recapitulates results about CD GS, then defines modified systems and shows that this combination has in most derivative modes equal strength to ET0L, except for terminating mode, which is shown to be more powerful. There are also explained examples of this new kind of systems.