On nilpotent languages and their characterization by regular expressions
Tree languages recognized by deterministic root-to-frontier recognizers are also called DR-languages. The concept of generalized R-chain languages was introduced by the author in his paper On monotone languages and their characterization by regular expressions (Acta Cybernetica, 18 (2007), 117-134.)...
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| Format: | Article |
| Published: |
2009
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| Series: | Acta cybernetica
19 No. 1 |
| Kulcsszavak: | Számítástechnika, Kibernetika |
| Subjects: | |
| doi: | 10.14232/actacyb.19.1.2009.15 |
| Online Access: | http://acta.bibl.u-szeged.hu/12863 |
| Summary: | Tree languages recognized by deterministic root-to-frontier recognizers are also called DR-languages. The concept of generalized R-chain languages was introduced by the author in his paper On monotone languages and their characterization by regular expressions (Acta Cybernetica, 18 (2007), 117-134.) and it has turned out that the monotone DR-languages are exactly those languages that can be given by generalized R-chain languages. In this paper we give a similar characterization for nilpotent DR-languages by means of plain R-chain languages. Also a regular expression based characterization is given for nilpotent string languages. |
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| Physical Description: | 231-244 |
| ISSN: | 0324-721X |