Two power-decreasing derivation restrictions in generalized scattered context grammars
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, le...
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| Main Authors: | |
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| Format: | Article |
| Published: |
2008
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| Series: | Acta cybernetica
18 No. 4 |
| Kulcsszavak: | Számítástechnika, Kibernetika |
| Subjects: | |
| Online Access: | http://acta.bibl.u-szeged.hu/12847 |
| Summary: | 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 power of context-free grammars. |
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| Physical Description: | 783-793 |
| ISSN: | 0324-721X |