On restricted context-free grammars

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985840%3A_____%2F12%3A00367493" target="_blank" >RIV/67985840:_____/12:00367493 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.1016/j.jcss.2011.05.008" target="_blank" >http://dx.doi.org/10.1016/j.jcss.2011.05.008</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.jcss.2011.05.008" target="_blank" >10.1016/j.jcss.2011.05.008</a>

Result language
angličtina
Original language name
On restricted context-free grammars
Original language description
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. Several regulations of the derivation process have been studied to increase the power of context-free grammars. In the resulting grammars, however, not only the symbols to be rewritten are restricted, but also the rules to be applied. In this paper, we study context-free grammars with a simpler restrictionwhere only symbols to be rewritten are restricted, not the rules, in the sense that any rule rewriting the chosen nonterminal can be applied. We prove that these grammars have the same power as random context, matrix, or programmed grammars. We also present two improved normal forms and discuss the characterization of context-sensitive languages by a variant using strings of length at most two instead of symbols.
Czech name
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Czech description
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Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BA - General mathematics
OECD FORD branch
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Publication year
2012
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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