Simple Semi-conditional Et0l Grammars
نویسندگان
چکیده
The present contribution introduces and studies simple semi-conditional ET0L grammars (SSC-ET0L grammars for short). It is demonstrated that SSC-ET0L grammars with permitting and forbidding conditions of length no more than one and two, respectively, generate all the family of recursively enumerable languages; if erasing productions are not allowed, these grammars generate precisely the family of context-sensitive languages.
منابع مشابه
A Note on the Generative Power of Some Simple Variants of Context-Free Grammars Regulated by Context Conditions
This paper answers three open questions concerning the generative power of some simple variants of context-free grammars regulated by context conditions. Specifically, it discusses the generative power of so-called contextfree semi-conditional grammars (which are random context grammars where permitting and forbidding sets are replaced with permitting and forbidding strings) where permitting an...
متن کاملCooperating Distributed Hyperedge Replacement Grammars
The concept of cooperation and distribution as known from the area of grammar systems is introduced to graph grammars; more precisely, to hyperedge replacement (for short, HR) grammars. This can be seen as a modest approach to controlled HR. Two diierent derivation modes are considered, the so called t-mode and the =k-mode. For the t-mode it is shown that the class of hypergraph languages obtai...
متن کاملSimple-Semi-Conditional Versions of Matrix Grammars with a Reduced Regulating Mechanism
This paper discusses some conditional versions of matrix grammars. It establishes several characterizations of the family of the recursively enumerable languages based on these grammars. In fact, making use of the Geffert Normal forms, the present paper demonstrates these characterizations based on matrix grammars with conditions of a limited length, a reduced number of nonterminals, and a redu...
متن کاملDescriptional complexity of semi-conditional grammars
The descriptional complexity of semi-conditional grammars is studied. It is proved that every recursively enumerable language is generated by a semi-conditional grammar of degree (2, 1) with no more than seven conditional productions and eight nonterminals.
متن کاملDescriptional Complexity of Grammars Regulated by Context Conditions
This paper improves several well-known results concerning the descriptional complexity of grammars regulated by context conditions. Specifically, it proves that every recursively enumerable language is generated (A) by a context-conditional grammar of degree (2, 1) with no more than seven conditional productions and eight nonterminals, (B) by a generalized forbidding grammar of degree two with ...
متن کامل