Schloss Dagstuhl - Leibniz-Zentrum für Informatik GmbH Schloss Dagstuhl - Leibniz-Zentrum für Informatik GmbH scholarly article en Thomas, Wolfgang; Christau, Julien; Löding, Christof License
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Deterministic Automata on Unranked Trees



We investigate bottom-up and top-down deterministic automata on unranked trees. We show that for an appropriate definition of bottom-up deterministic automata it is possible to minimize the number of states efficiently and to obtain a unique canonical representative of the accepted tree language. For top-down deterministic automata it is well known that they are less expressive than the non-deterministic ones. By generalizing a corresponding proof from the theory of ranked tree automata we show that it is decidable whether a given regular language of unranked trees can be recognized by a top-down deterministic automaton. The standard deterministic top-down model is slightly weaker than the model we use, where at each node the automaton can scan the sequence of the labels of its successors before deciding its next move.

BibTeX - Entry

  author =	{Wolfgang Thomas and Julien Christau and Christof L{\"o}ding},
  title =	{Deterministic Automata on Unranked Trees},
  booktitle =	{Foundations of Semistructured Data},
  year =	{2005},
  editor =	{Frank Neven and Thomas Schwentick and Dan Suciu},
  number =	{05061},
  series =	{Dagstuhl Seminar Proceedings},
  ISSN =	{1862-4405},
  publisher =	{Internationales Begegnungs- und Forschungszentrum f{\"u}r Informatik (IBFI), Schloss Dagstuhl, Germany},
  address =	{Dagstuhl, Germany},
  URL =		{},
  annote =	{Keywords: Automata, unranked trees, parikh automata}

Keywords: Automata, unranked trees, parikh automata
Seminar: 05061 - Foundations of Semistructured Data
Issue date: 2005
Date of publication: 10.08.2005

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