Journal ArticleDOI
The linear landscape of external contextual languages
TLDR
A characterization of linear languages and a whole landscape of sublinear families is obtained by restricting the contexts to be one-sided (only left-sided or only right-sided) and a characterization of regular languages — here the subregular landscape reduces to two families.Abstract:
The class of external contextual languages isstrictly included in the class of linear languages. A reason for the strict inclusion in linear languages is that external contextual grammars generate languages in the exhaustive way: each sentential form belongs to the language of a grammar.
In this paper we study the effect of adding various squeezing mechanisms to the basic classes of exhaustive contextual grammars. We obtain in this way a characterization of linear languages and a whole landscape of sublinear families. By restricting the contexts to be one-sided (only left-sided or only right-sided) we obtain a characterization of regular languages -- here the subregular landscape reduces to two families.read more
Citations
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Book ChapterDOI
Contextual grammars and formal languages
TL;DR: The chapter by S. Marcus in this handbook gives a lucid account of the motivation behind contextual grammars from the natural point of view.
Journal ArticleDOI
On representing recursively enumerable languages by internal contextual languages
TL;DR: It is proved that each recursively enumerable language L can be written in the form L = cut c ( L 0 ∩ R ), where L 0 is an internal contextual language, R is a regular language, and cut c is the operation which for a word x removes the prefix of x to the left of the unique occurrence of ± in x .
Journal Article
Representations of Recursively Enumerable Array Languages by Contextual Array Grammars
TL;DR: The main result proved shows that the natural embedding of any recursively enumerable one-dimensional array language in the two-dimensional space can be characterized by the projection of a two- dimensional array language generated by a contextual array grammar working in the t-mode and with norm one.
Journal ArticleDOI
One-dimensional Array Grammars and P Systems with Array Insertion and Deletion Rules
TL;DR: The main result of the paper exhibits computational completeness of one-dimensional array grammars using array insertion and deletion rules of norm at least two and even of norm one only.
Book ChapterDOI
Array Insertion and Deletion P Systems
TL;DR: It is shown that two-dimensional array insertion and deletion P systems can already obtain computational completeness using such P systems with a membrane structure of tree height of at most two and only the targets here, in, and out.
References
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Journal ArticleDOI
Reversal-bounded multipushdown machines
Brenda S. Baker,Ronald V. Book +1 more
TL;DR: Several representations of the recursively enumerable (r.e.) sets are presented and it is shown that this automata theoretic representation cannot be strengthened by restricting the acceptors to be deterministic multitape, nondeterministic one-tape, or nondetergetic multicounter acceptors.
Book
Marcus Contextual Grammars
Gheorghe Paun,Gheorghe Pun +1 more
TL;DR: 1. Origin and Motivation, Formal Language Theory Prerequisites, and A Generalization: n-Contextual Grammars.
Journal ArticleDOI
Contextual grammars: parallelism and blocking of derivation
TL;DR: This work considers contextual grammars with parallel derivations, in which the whole current string participates to a derivation step in the sense that it is splitted into substrings to which contexts are adjoined in a parallel manner.