Acta Informatica

, Volume 6, Issue 4, pp 407–415 | Cite as

On proving that certain languages are not ETOL

  • A. Ehrenfeucht
  • G. Rozenberg


In this paper a partial characterization for a subclass of ETOL languages is obtained. The main result binds together the number of occurrences (in words of a given ETOL language) of letters, from a given set, with their distribution. It provides a very helpful tool to prove that certain languages are not ETOL.


Information System Operating System Data Structure Communication Network Information Theory 
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 1976

Authors and Affiliations

  • A. Ehrenfeucht
    • 1
  • G. Rozenberg
    • 2
  1. 1.Department of Computer ScienceUniversity of Colorado at BoulderBoulderUSA
  2. 2.Institute of MathematicsUtrecht UniversityUtrecht-UithofThe Netherlands

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