On the computational completeness of context-free parallel communicating grammar systems
نویسندگان
چکیده
منابع مشابه
On the Computational Completeness of Context-Free Parallel Communicating Grammar Systems
We prove that all recursively enumerable languages can be generated by context-free returning parallel communicating grammar systems by showing how the parallel communicating grammars can simulate two-counter machines, a class of Turing machine variants which is known to be computationally complete. Moreover, we prove that systems with a bounded number of components are suucient to reach this g...
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Two contradictory results state that the synchronized parallel communicating grammar systems with context-free components (CF-PCGS) are either Turing complete or less expressive than contextsensitive grammars. We show that the latter result is incorrect. Indeed, we discover that the proof of this result relies on coverability trees for CF-PCGS, but that such coverability trees do not contain en...
متن کاملOn context-free parallel communicating grammar systems: synchronization, communication, and normal forms
In this paper we study the generative power of context-free returning parallel communicating grammar systems using diierent synchronization mechanisms and communication protocols. We demonstrate the equivalence of several types of these systems and present normal form theorems showing that all languages generated by context-free returning parallel communicating grammar systems can also be gener...
متن کاملRemarks on Context-Free Parallel Communicating Grammar Systems Generating Crossed Agreements
When modeling natural languages, three phenomena should be considered: the so-called multiple agreements, crossed agreements and replication. These aspects are represented by the three languages K1 = { a nbncn | n ≥ 1 }, K2 = { a nbmcndm | m ≥ 1, n ≥ 1 }, and K3 = {ww |w ∈ { a, b } + }, respectively. In the present paper, we give parallel communicating grammar systems (PC grammar systems) that ...
متن کاملCompleteness of Context-Free Grammar Forms
The notions of a grammar form and g-interpretation were first introduced in [2]. However, it quickly became apparent, particularly for EOL forms [5], that (strict) interpretations had a wider interest as well as being better motivated mathematically. The study of parsing of grammar forms detailed in [4], the basic investigation in [8] on linear completeness amongst other results, the study of d...
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 1999
ISSN: 0304-3975
DOI: 10.1016/s0304-3975(98)00193-5