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On Reversible Transducers Dartois, Luc Fournier, Paulin Jecker, Ismaël Lhote, Nathan Transducers reversibility two-way uniformization Deterministic two-way transducers define the robust class of regular functions which is, among other good properties, closed under composition. However, the best known algorithms for composing two-way transducers cause a double exponential blow-up in the size of the inputs. In this paper, we introduce a class of transducers for which the composition has polynomial complexity. It is the class of reversible transducers, for which the computation steps can be reversed deterministically. While in the one-way setting this class is not very expressive, we prove that any two-way transducer can be made reversible through a single exponential blow-up. As a consequence, we prove that the composition of two-way transducers can be done with a single exponential blow-up in the number of states. A uniformization of a relation is a function with the same domain and which is included in the original relation. Our main result actually states that we can uniformize any non-deterministic two-way transducer by a reversible transducer with a single exponential blow-up, improving the known result by de Souza which has a quadruple exponential complexity. As a side result, our construction also gives a quadratic transformation from copyless streaming string transducers to two-way transducers, improving the exponential previous bound. Schloss Dagstuhl – Leibniz-Zentrum für Informatik Luc Dartois and Paulin Fournier and Ismaël Jecker and Nathan Lhote 2017 Is Part Of LIPIcs, Volume 80, 44th International Colloquium on Automata, Languages, and Programming (ICALP 2017) InProceedings Text doc-type:ResearchArticle publishedVersion application/pdf doi:10.4230/LIPIcs.ICALP.2017.113 urn:nbn:de:0030-drops-74491 https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2017.113 eng https://creativecommons.org/licenses/by/3.0/legalcode