Two Power-Decreasing Derivation Restrictions in Generalized Scattered Context Grammars
Result description
The present paper introduces and discusses generalized scattered context grammars that are based upon sequences of productions whose left-hand sides are formed by nonterminal strings, not just single nonterminals. It places two restrictions on the derivations in these grammars. More specifically, let k be a positive integer. The first restriction requires that all rewritten symbols occur within the first k symbols of the first continuous block of nonterminals in the sentential form during every derivation step. The other restriction defines derivations over sentential forms containing no more than k occurrences of nonterminals. As its main result, the paper demonstrates that both restrictions decrease the generative power of these grammars to the powerof context-free grammars.
Keywords
scattered context grammargrammatical generalizationderivation restrictiongenerative power
The result's identifiers
Result code in IS VaVaI
Result on the web
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DOI - Digital Object Identifier
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Alternative languages
Result language
angličtina
Original language name
Two Power-Decreasing Derivation Restrictions in Generalized Scattered Context Grammars
Original language description
The present paper introduces and discusses generalized scattered context grammars that are based upon sequences of productions whose left-hand sides are formed by nonterminal strings, not just single nonterminals. It places two restrictions on the derivations in these grammars. More specifically, let k be a positive integer. The first restriction requires that all rewritten symbols occur within the first k symbols of the first continuous block of nonterminals in the sentential form during every derivation step. The other restriction defines derivations over sentential forms containing no more than k occurrences of nonterminals. As its main result, the paper demonstrates that both restrictions decrease the generative power of these grammars to the powerof context-free grammars.
Czech name
Dvě omezení snižující sílu zobecněných gramatik s rozptýleným kontextem
Czech description
Článek zavádí a diskutuje zobecněné gramatiky s rozptýleným kontextem založené na sekvencích pravidel, jejichž levé strany jsou tvořeny řetězci neterminálů místo standardního jednoho neterminálu. Studovány jsou dvě omezení v těchto gramatikách. První omezení vyžaduje, aby se všechny přepisované symboly jakéhokoliv derivačního kroku vyskytovaly v prvních k symbolech prvního souvislého bloku neterminálů. Druhé pak definuje derivace, jejichž jednotlivé větné formy nemají více než k neterminálů. Hlavním výsledkem článku je, že obě omezení vedou ke snížení síly těchto gramatik na sílu bezkontextových gramatik.
Classification
Type
Jx - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BD - Information theory
OECD FORD branch
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Result continuities
Project
GA201/07/0005: Multi-information technologies: Theory, models, and methods
Continuities
Z - Vyzkumny zamer (s odkazem do CEZ)
Others
Publication year
2008
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Acta Cybernetica
ISSN
0324-721X
e-ISSN
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Volume of the periodical
18
Issue of the periodical within the volume
4
Country of publishing house
US - UNITED STATES
Number of pages
11
Pages from-to
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UT code for WoS article
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EID of the result in the Scopus database
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Basic information
Result type
Jx - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP
BD - Information theory
Year of implementation
2008