Some results on RWW- and RRWW-automata and their relation to the class of growing context-sensitive languages

  • Authors:

  • Tomasz Jurdziński;Krzysztof Lorys;Gundula Niemann;Friedrich Otto

  • Affiliations:

  • Fachbereich Mathematik/Informatik, Universität Kassel and Institute of Computer Science, University of Wrocław, Wrocław, Poland;Institute of Computer Science, University of Wrocław, Wrocław, Poland;Fachbereich Mathematik/Informatik, Universität Kassel, Kassel, Germany and SAP Deutschland;Fachbereich Mathematik/Informatik, Universität Kassel, Kassel, Germany

  • Venue:
  • Journal of Automata, Languages and Combinatorics
  • Year:
  • 2004

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Abstract

It is shown that already the RWW-automata of Jancar et al (1998) accept the Gladkij language LG1 = {w#wR#w | w {a, b}*}, which implies that the class GCSL of growing context-sensitive languages is a proper subclass of the class L(RWW) of languages accepted by the RWW-automata. In addition, it is shown that L(RWW) contains an NP-complete language. Also a simple reduction from the class L(RRWW) of languages accepted by the RRWW-automata to the class L(RWW) is presented, which indicates that these two classes will be hard to separate if they are not identical. Finally, characterizations of the class GCSL in terms of restricted versions of the RWW- and the RRWW-automata are given.