Fixed Point Approach to Commutation of Languages

  • Karel CulikII
  • Juhani Karhumäki
  • Petri Salmela
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2950)


We show that the maximal set commuting with a given regular set – its centralizer – can be defined as the maximal fixed point of a certain language operator. Unfortunately, however, an infinite number of iterations might be needed even in the case of finite languages.


Regular Language Point Approach Free Semigroup Language Operator Left Quotient 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Karel CulikII
    • 1
  • Juhani Karhumäki
    • 2
  • Petri Salmela
    • 2
  1. 1.Department of Computer ScienceUniversity of South CarolinaColumbiaUSA
  2. 2.Department of Mathematics and, Turku Centre for Computer ScienceUniversity of TurkuTurkuFinland

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