A note on scattered context grammars
نویسندگان
چکیده
منابع مشابه
Scattered Context Grammars with Regulation
In this paper, we consider generating and accepting (unordered) scattered context grammars with unconditional transfer and characterize the such-deened language classes, comparing them mutually and with classes of the Chomsky hierarchy and several versions of programmed grammars.
متن کاملOn the descriptional complexity of scattered context grammars
This paper proves that every recursively enumerable language is generated by a scattered context grammar with no more than four nonterminals and three non-context-free productions. In its conclusion, it gives an overview of the results and open problems concerning scattered context grammars and languages.
متن کاملLeftmost Derivations of Propagating Scattered Context Grammars: A New Proof
Propagating scattered context grammars, introduced in [3], represent an important type of semi-parallel rewriting systems. Since their introduction, however, the exact relationship of the family of languages they generate to the family of context-sensitive languages is unknown. The language family generated by these grammars is included in the family of context-sensitive languages; on the other...
متن کاملA note on one-sided context-sensitive grammars
In this note it is proved that so called one-sided context-sensitive grammars can generate languages which cannot be generated by any context-free grammar. This fact is not quite new. It has been proved in [3], [4] and [5] (as far as the author knows). In [3] it is proved that a special one-sided context-sensitive grammar suggested by Dr. Fris ([1]) generates a language {a m b'"c"; Hn^ m} which...
متن کاملA Note on Context-free Grammars with Rewriting Restrictions∗
In this work two special types of random context grammars are investigated. In one of these grammars one can apply a context-free rule to a nonterminal A only if the current sentential form does not contain a particular nonterminal associated toA. The other grammar works in the opposite direction, it requires the presence of the associated nonterminal to apply the rule. Here we show that these ...
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ژورنال
عنوان ژورنال: Information Processing Letters
سال: 1971
ISSN: 0020-0190
DOI: 10.1016/0020-0190(71)90004-4