SZTE Repository of Papers and Books: No conditions. Results ordered -Date Deposited. 2020-11-29T15:46:23ZEPrintshttp://acta.bibl.u-szeged.hu/images/acta.jpghttp://acta.bibl.u-szeged.hu/2016-10-15T12:25:30Z2018-06-05T15:04:58Zhttp://acta.bibl.u-szeged.hu/id/eprint/12775This item is in the repository with the URL: http://acta.bibl.u-szeged.hu/id/eprint/127752016-10-15T12:25:30ZOn the closedness of nilpotent DR tree languages under Boolean operationsThis note deals with the closedness of nilpotent deterministic root-to-frontier tree languages with respect to the Boolean operations union, intersection and complementation. Necessary and sufficient conditions are given under which the union of two deterministic tree languages is also deterministic. The paper ends with a characterization of the largest subclass of the
class of nilpotent deterministic root-to-frontier tree languages closed under the formation of complements.Ferenc GécsegGyörgy Gyurica2016-10-15T12:25:26Z2018-06-05T13:57:38Zhttp://acta.bibl.u-szeged.hu/id/eprint/12806This item is in the repository with the URL: http://acta.bibl.u-szeged.hu/id/eprint/128062016-10-15T12:25:26ZOn monotone languages and their characterization by regular expressionsIn one of their papers, F. Gécseg and B. Imreh gave a characterization for monotone string languages by regular expressions. It has turned out that the monotone string languages are exactly those languages that can be represented by finite unions of seminormal chain languages. In this paper a similar characterization is given for monotone DR-languages.György Gyurica2016-10-15T12:25:03Z2018-06-06T10:10:16Zhttp://acta.bibl.u-szeged.hu/id/eprint/12863This item is in the repository with the URL: http://acta.bibl.u-szeged.hu/id/eprint/128632016-10-15T12:25:03ZOn nilpotent languages and their characterization by regular expressionsTree 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.György Gyurica