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On Well Quasi-orders on Languages

  • Flavio D’Alessandro
  • Stefano Varricchio
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2710)

Abstract

Let G be a context-free grammar and let L be the language of all the words derived from any variable of G. We prove the following generalization of Higman’s theorem: any division order on L is a well quasi-order on L. We also give applications of this result to some quasi-orders associated with unitary grammars.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Flavio D’Alessandro
    • 1
  • Stefano Varricchio
    • 2
  1. 1.Dipartimento di MatematicaUniversità di Roma “La Sapienza”RomaItaly
  2. 2.Dipartimento di MatematicaUniversità di Roma “Tor Vergata”RomaItaly

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