Generalized One-Unambiguity

  • Pascal Caron
  • Yo-Sub Han
  • Ludovic Mignot
Part of the Lecture Notes in Computer Science book series (LNCS, volume 6795)


Brüggemann-Klein and Wood have introduced a new family of regular languages, the one-unambiguous regular languages, a very important notion in XML DTDs. A regular language L is one-unambiguous if and only if there exists a regular expression E over the operators of sum, catenation and Kleene star such that L(E) = L and the position automaton of E is deterministic. It implies that for a one-unambiguous expression, there exists an equivalent linear-size deterministic recognizer. In this paper, we extend the notion of one-unambiguity to weak one-unambiguity over regular expressions using the complement operator ¬. We show that a DFA with at most (n + 2) states can be computed from a weakly one-unambiguous expression and that it is decidable whether or not a given DFA recognizes a weakly one-unambiguous language.


Regular Expression Transverse Property Regular Language Closure Property Sink State 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Pascal Caron
    • 1
  • Yo-Sub Han
    • 2
  • Ludovic Mignot
    • 1
  1. 1.LITISUniversité de RouenSaint-Étienne du Rouvray CedexFrance
  2. 2.Dept. of Computer ScienceYonsei UniversitySeoulRepublic of Korea

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