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Minimizing Tree Automata for Unranked Trees

Abstract : Automata for unranked trees form a foundation for XML schemas, querying and pattern languages. We study the problem of efficiently minimizing such automata. We start with the unranked tree automata (UTAs) that are standard in database theory, assuming bottom-up determinism and that horizontal recursion is represented by deterministic finite automata. We show that minimal UTAs in that class are not unique and that minimization is NP-hard. We then study more recent automata classes that do allow for polynomial time minimization. Among those, we show that bottom-up deterministic stepwise tree automata yield the most succinct representations.
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Contributor : Joachim Niehren Connect in order to contact the contributor
Submitted on : Tuesday, November 16, 2010 - 1:32:06 PM
Last modification on : Friday, February 4, 2022 - 3:19:17 AM
Long-term archiving on: : Thursday, February 17, 2011 - 2:57:38 AM


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  • HAL Id : inria-00536521, version 1



Wim Martens, Joachim Niehren. Minimizing Tree Automata for Unranked Trees. 10th International Symposium on Database Programming Languages, 2005, Trondheim, Norway. pp.232--246. ⟨inria-00536521⟩



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