Structurally Unambiguous Finite Automata

  • Hing Leung
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4094)


We define a structurally unambiguous finite automaton (SUFA) to be a nondeterministic finite automaton (NFA) with one starting state q 0 such that for all input strings w and for any state q, there is at most one path from q 0 to q that consumes w. The definition of SUFA differs from the usual definition of an unambiguous finite automaton (UFA) in that the new definition is defined in terms of the transition logic of the finite automaton, and is independent of the choice of final states. We show that SUFA can be exponentially more succinct in the number of states than UFA and MDFA (deterministic finite automata with multiple initial states). Some interesting examples of SUFA are given. We argue that SUFA is a meaningful concept, and can have practical importance as it can implemented efficiently on synchronous models of parallel computation.


Transition Logic Starting State Equivalence Problem Regular Language Input String 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Hing Leung
    • 1
  1. 1.Department of Computer ScienceNew Mexico State UniversityLas CrucesU.S.A.

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