Mathematical systems theory

, Volume 27, Issue 4, pp 285–346 | Cite as

Equivalence of finite-valued tree transducers is decidable

  • H. Seidl


A bottom-up finite state tree transducer (FST) M is calledk-valued iff for every input tree there are at mostk different output trees.M is called finite-valued iff it isk-valued for somek. We show that it is decidable for everyk whether or not a given FST M isk-valued. We give an effective characterization of all finite-valued FSTs and derive a (sharp) upper bound for the valuedness provided it is finite. We decompose a finite-valued FSTM into a finite number of single-valued FSTs. This enables us to prove: it is decidable whether or not the translation of an FSTM is included in the translation of a finite-valued FSTM'. We also consider these questions for size-valuedness.


State Tree Computational Mathematic Finite Number Input Tree Output Tree 
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Copyright information

© Springer-Verlag New York Inc. 1994

Authors and Affiliations

  • H. Seidl
    • 1
  1. 1.Fachbereich InformatikUniversität des SaarlandesSaarbrückenGermany

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