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标题：Origin-Equivalence of Two-Way Word Transducers Is in PSPACE
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作者：Sougata Bose ; Anca Muscholl ; Vincent Penelle 等
期刊名称：LIPIcs : Leibniz International Proceedings in Informatics
电子版ISSN：1868-8969
出版年度：2018
卷号：122
页码：1-18
DOI：10.4230/LIPIcs.FSTTCS.2018.22
出版社：Schloss Dagstuhl -- Leibniz-Zentrum fuer Informatik
摘要：We consider equivalence and containment problems for word transductions. These problems are known to be undecidable when the transductions are relations between words realized by non-deterministic transducers, and become decidable when restricting to functions from words to words. Here we prove that decidability can be equally recovered the origin semantics, that was introduced by Bojanczyk in 2014. We prove that the equivalence and containment problems for two-way word transducers in the origin semantics are PSPACE-complete. We also consider a variant of the containment problem where two-way transducers are compared under the origin semantics, but in a more relaxed way, by allowing distortions of the origins. The possible distortions are described by means of a resynchronization relation. We propose MSO-definable resynchronizers and show that they preserve the decidability of the containment problem under resynchronizations. {}
关键词：Transducers; origin semantics; equivalence