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The unsolvability of the equality problem for sentential forms of context-free grammars

Meera Blattner
1973 Journal of computer and system sciences (Print)  
Three results which follow are: (i) The equality problem for sentential forms of c-finite grammars is unsolvable, and therefore the equality problem for the sentential forms of context-free grammars is  ...  (ii) The equality problem for sentential forms of bounded context-free grammars is unsolvable. (iii) The equality problem for OL-languages is unsolvable.  ...  We can now see that the sentential forms of context-free grammars are OLlanguages.  ... 
doi:10.1016/s0022-0000(73)80002-9 fatcat:6qla7qr74jbpfau5lwzoddjunq

On context-free parallel communicating grammar systems: synchronization, communication, and normal forms

Erzsébet Csuhaj-Varjú, György Vaszil
2001 Theoretical Computer Science  
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  ...  In this paper we study the generative power of context-free returning parallel communicating grammar systems using di erent synchronization mechanisms and communication protocols.  ...  Let be a context-free returning PC grammar system where each production contains at most one query symbol on its right-hand side.  ... 
doi:10.1016/s0304-3975(99)00318-7 fatcat:ihjuijzi7vdypiuq5gcjq5nggu

Computing by Only Observing [chapter]

Matteo Cavaliere, Pierluigi Frisco, Hendrik Jan Hoogeboom
2006 Lecture Notes in Computer Science  
We consider grammars as basic systems combined with finite state automata as observers, watching either the sequence of sentential forms or the productions used by the grammar.  ...  It is possible to obtain computational completeness only varying the observer, without modifying the basic system, which is a fixed context-free grammar.  ...  Parts of this research was performed while M. Cavaliere, PhD student at University of Seville, was visiting the Leiden Institute for Advanced Computer Science during the Spring of 2005.  ... 
doi:10.1007/11779148_28 fatcat:oqwrdgub6reuzmeumtojwyc6ne

Parallel communicating grammar systems with bounded resources

Erzsébet Csuhaj-Varjú, György Vaszil
2002 Theoretical Computer Science  
In this paper we study size properties of context-free returning parallel communicating grammar systems (PC grammar systems).  ...  We show that for each context-free returning PC grammar system an equivalent system of this type can be constructed, where the total number of symbols used for describing a component can be bounded by  ...  For each context-free returning PC grammar system we can construct an equivalent context-free returning PC grammar system such that CProd( )67. Proof.  ... 
doi:10.1016/s0304-3975(01)00172-4 fatcat:thyzvycgabgfrp2bks6f76cwse

Structural similarity in context-free languages

Meera Blattner
1976 Information and Control  
set of sentential forms; (4) there is a nonempty equivalence class of structurally similar languages that contains no (right) sentential forms of any grammar; (5) if an equivalence class contains any set  ...  of (right) sentential forms at all then every language in the class has a set of (right) sentential forms in that class.  ...  ACKNOWLEDGMENT Much of the material found in this paper is from my dissertation. I am deeply grateful to my advisor, Professor Sheila Greibach, for her guidance.  ... 
doi:10.1016/s0019-9958(76)90518-0 fatcat:j57mltfnmjarxkajxdphoa5xyi

On restricted context-free grammars

Jürgen Dassow, Tomáš Masopust
2012 Journal of computer and system sciences (Print)  
Context-free grammars are widely used for the simple form of their rules.  ...  A derivation step consists of the choice of a nonterminal of the sentential form and of an application of a rule rewriting it.  ...  Acknowledgments The authors gratefully acknowledge very useful suggestions and comments of the anonymous referees.  ... 
doi:10.1016/j.jcss.2011.05.008 fatcat:prs76bxqfrbujchmsbb3tmclz4

Bounded context parsable grammars

John H. Williams
1975 Information and Control  
In this paper we extend Floyd's notion of parsing by bounded context to define the Bounded Context Parsable Grammars, a class of recursive subsets of context free grammars for which we can construct linear  ...  It is shown that the set of languages of the grammars thus defined properly contains the set of deterministic languages without the empty sentence.  ...  context, and the BCP grammars ensure only that at least one simple phrase of every sentential form occurs in a parsing context.  ... 
doi:10.1016/s0019-9958(75)90330-7 fatcat:zeds2d4jpveqhnmuduuc2k2jpq

Simple restriction in context-free rewriting

Tomáš Masopust
2010 Journal of computer and system sciences (Print)  
On one hand, these systems preserve the simplicity of applications of context-free productions and, on the other hand, they increase the generative power to cover more aspects of natural and programming  ...  form, while if coupled with −, it must not appear in the sentential form.  ...  This work was supported by the Czech Ministry of Education under the Research Plan No. MSM 0021630528.  ... 
doi:10.1016/j.jcss.2010.04.001 fatcat:6vdedx2lhbanhhoi76kollnjnm

Van Wijngaarden grammars, metamorphism and K-ary malwares [article]

Geoffroy Gueguen
2010 arXiv   pre-print
Grammars are used to describe sentences structure, thanks to some sets of rules, which depends on the grammar type.  ...  As their name suggests it, the main idea behind these grammars is that they are composed of two grammars. Van Wijngaarden grammars, particularly, are such grammars.  ...  Acknowledgement The author would like to thank Eric Filiol for his fruitful discussions about formal grammars, his active support to this work and all the people at the Operational Cryptology and Virology  ... 
arXiv:1009.4012v1 fatcat:txgk6k6nsnbonpfpwqhahkes7u

On the descriptional complexity of some rewriting mechanisms regulated by context conditions

György Vaszil
2005 Theoretical Computer Science  
The results are based on the common idea of using the so called Geffert normal forms for phrase structure grammars.  ...  We improve the upper bounds of certain descriptional complexity measures of two types of rewriting mechanisms regulated by context conditions.  ...  The productions of these grammars are ordered sequences of context-free rewriting rules which have to be applied in parallel on nonterminals appearing in the sentential form in the same order as the nonterminals  ... 
doi:10.1016/j.tcs.2004.06.032 fatcat:gjug6gbcljgstcm6rlh7dprcjm

Phrase structure grammars generating context-free languages

Robert L. Cannon
1975 Information and Control  
As an indication of the utility of this approach, it is used to describe a condition u n d e r which the language generated by a phrase structure grammar 1 will be context-free. 2 1 Aphrase structuregrammar  ...  H e has noted the use of a derivation tree as a structural description for generation by a context-free g r a m m a r and the lack of a similar mechanism for describing context-sensitive generation.  ...  of the rightmost (leffmost) nonterminal symbol in a sentential form, then the grammar still generates a context-free language.  ... 
doi:10.1016/s0019-9958(75)90426-x fatcat:cwsmze4t4bbpfaavrye6unlacm

Page 2255 of Mathematical Reviews Vol. 52, Issue 6 [page]

1976 Mathematical Reviews  
The author considers when a language L is structurally similar to the set of sentential forms of some (context-free) grammar.  ...  A context-free grammar in Greibach normal form is called separated if each terminal symbol occurs in at most one produc- tion.  ... 

The relation between derivations and syntactical structures in phrase-structure grammars

Jürgen Eickel, Jacques Loeckx
1972 Journal of computer and system sciences (Print)  
The simplifications for the particular cases of contextsensitive and context-free grammars are indicated.  ...  Conditions for a phrase-structure grammar (Chomsky 0-type grammar) are established which warrant that any of its derivations univocally defines a syntactical structure of the sentence.  ...  Call L the set of all sentential forms of the context-free grammar and put M = V*" {A}. {(78)~+11k >~ 0}" {yB}. V*. (see Footnote 7.)  ... 
doi:10.1016/s0022-0000(72)80006-0 fatcat:f2akjxq62rg6vhuh76hhhdouxu

On the computational completeness of context-free parallel communicating grammar systems

Erzsébet Csuhaj-Varjú, György Vaszil
1999 Theoretical Computer Science  
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.  ...  The power of context-free PC grammar systems In this section we show that the class of recursively enumerable languages is equal to the class of languages generated by context-free returning PC grammar  ... 
doi:10.1016/s0304-3975(98)00193-5 fatcat:uuu3eiez4vdzbmli2x5tkm2qwm

Cooperating Distributed Grammar Systems: Components with Nonincreasing Competence [chapter]

Maurice H. ter Beek, Erzsébet Csuhaj-Varjú, Markus Holzer, György Vaszil
2011 Lecture Notes in Computer Science  
We study the generative power of CD grammar systems (CDGSs) that use a cooperation protocol based on the level of competence on a sentential form -and the competence of their components does not increase  ...  cooperation protocol, for various k, with that of context-free forbidding random context grammars, (random context) ET0L systems, and context-free programmed grammars with appearance checking.  ...  Acknowledgements We thank an anonymous referee of [7] for suggesting to consider also a dynamic definition of nonincreasing competence-based derivation.  ... 
doi:10.1007/978-3-642-20000-7_7 fatcat:anqokasphzckhbcuz62547fhei
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