Parameter Reduction in Grammar-Compressed Trees

  • Markus Lohrey
  • Sebastian Maneth
  • Manfred Schmidt-Schauß
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5504)


Trees can be conveniently compressed with linear straight-line context-free tree grammars. Such grammars generalize straight-line context-free string grammars which are widely used in the development of algorithms that execute directly on compressed structures (without prior decompression). It is shown that every linear straight-line context-free tree grammar can be transformed in polynomial time into a monadic (and linear) one. A tree grammar is monadic if each nonterminal uses at most one context parameter. Based on this result, a polynomial time algorithm is presented for testing whether a given nondeterministic tree automaton with sibling constraints accepts a tree given by a linear straight-line context-free tree grammar. It is shown that if tree grammars are nondeterministic or non-linear, then reducing their numbers of parameters cannot be done without an exponential blow-up in grammar size.


Polynomial Time Polynomial Time Algorithm Maximal Rank Tree Automaton Context Parameter 
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 2009

Authors and Affiliations

  • Markus Lohrey
    • 1
  • Sebastian Maneth
    • 2
  • Manfred Schmidt-Schauß
    • 3
  1. 1.Institut für InformatikUniversität LeipzigGermany
  2. 2.NICTA and University of New South WalesAustralia
  3. 3.Institut für InformatikJohann Wolfgang Goethe-Universität FrankfurtGermany

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