Derivation "Trees" and Parallelism in Chomsky-Type Grammars

• Autores: Benedek Nagy
• Localización: Triangle: Language, Literature, Computation = Lenguaje, Literatura, Computación = Llenguatge, Literatura, Computació, ISSN 2013-939X, Nº. 8, 2012 (Ejemplar dedicado a: Languages : Mathematical Approaches / María Dolores Jiménez-López (ed. lit.)), págs. 101-120
• Idioma: inglés
• Enlaces
  • Texto completo
• Resumen

  • In this paper we discuss parallel derivations for context-free, contextsensitive and phrase-structure grammars. For regular and linear grammars only sequential derivation can be applied, but a kind of parallelism is present in linear grammars. We show that nite languages can be generated by a recursion-free rule-set. It is well-known that in context-free grammars the derivation can be in maximal (independent) parallel way. We show that in cases of context-sensitive and recursively enumerable languages the parallel branches of the derivation have some synchronization points. In the case of context-sensitive grammars this synchronization can only be local, but in a derivation of an arbitrary grammar we cannot make this restriction. We present a framework to show how the concept of parallelism can be t to the derivations in formal language theory using tokens.