Intersections of some families of languages

  • Franz J. Brandenburg
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 226)


What do a pushdown and a queue have in common? What is their intersection? Is it a counter? If we add the one-reversal restriction, is a one-reversal counter exactly the intersection of a one-reversal pushdown and a queue or, symmetrically, the intersection of a one-reset tape and a pushdown? These and similar assumptions can be heard here and there, and there are some conjectures by Autebert et al. [1], Book et al. [3] and Rodriguez

We disprove all these conjectures and show that counters are strictly weaker than the intersection of pushdowns and queues. This goes through for the restriction to one reversal or one reset. In fact, we obtain new families of languages from intersections of some well-known families.


Strict Inclusion Input Tape Machine Counter Formal Language Theory Iteration Property 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1986

Authors and Affiliations

  • Franz J. Brandenburg
    • 1
  1. 1.Lehrstuhl für InformatikUniversität PassauPassauF.R. Germany

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