Compressed Tree Canonization

  • Markus Lohrey
  • Sebastian Maneth
  • Fabian Peternek
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 9135)


Straight-line (linear) context-free tree (slt) grammars have been used to compactly represent ordered trees. Equivalence of slt grammars is decidable in polynomial time. Here we extend this result and show that isomorphism of unordered trees given as slt grammars is decidable in polynomial time. The result generalizes to isomorphism of unrooted trees and bisimulation equivalence. For non-linear slt grammars which can have double-exponential compression ratios, we prove that unordered isomorphism and bisimulation equivalence are \(\textsc {pspace}\)-hard and in \(\textsc {exptime}\).


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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Markus Lohrey
    • 1
  • Sebastian Maneth
    • 2
  • Fabian Peternek
    • 2
  1. 1.Universität SiegenSiegenGermany
  2. 2.University of EdinburghEdinburghUK

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