Deciding Equivalence of Linear Tree-to-Word Transducers in Polynomial Time
We show that the equivalence of linear top-down tree-to-word transducers is decidable in polynomial time. Linear tree-to-word transducers are non-copying but not necessarily order-preserving and can be used to express XML and other document transformations. The result is based on a partial normal form that provides a basic characterization of the languages produced by linear tree-to-word transducers.
KeywordsTree transducer Deciding equivalence Partial normal form
We would like to thank the reviewers for their very helpful comments.
- 2.Engelfriet, J.: Some open question and recent results on tree transducers and tree languages. In: Book, R.V. (ed.) Formal Language Theory, Perspectives and Open Problems, pp. 241–286. Academic Press, New York (1980)Google Scholar
- 5.Engelfriet, J., Rozenberg, G., Slutzki, G.: Tree transducers, L systems and two-way machines. In: Proceedings of the Tenth Annual ACM Symposium on Theory of Computing, pp. 66–74. ACM (1978)Google Scholar
- 8.Lemay, A., Maneth, S., Niehren, J.: A learning algorithm for top-down XML transformations. In: Proceedings of the Twenty-Ninth ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems, pp. 285–296 (2010)Google Scholar
- 10.Maneth, S., Seidl, H.: Deciding equivalence of top-down XML transformations in polynomial time. In: Programming Language Technologies for XML, pp. 73–79 (2007)Google Scholar
- 11.Plandowski, W.: The complexity of the morphism equivalence problem for context-free languages. Ph.D. thesis, Warsaw University (1995)Google Scholar
- 12.Seidl, H., Maneth, S., Kemper, G.: Equivalence of deterministic top-down tree-to-string transducers is decidable. In: IEEE 56th Annual Symposium on Foundations of Computer Science, pp. 943–962 (2015)Google Scholar