,
Paul Gastin
,
Loïc Germerie Guizouarn
,
R. Govind
,
Shankaranarayanan Krishna
Creative Commons Attribution 4.0 International license
Deterministic two-way transducers capture the class of regular functions. The efficiency of composing two-way transducers has a direct implication in algorithmic problems related to synthesis, where transformation specifications are converted into equivalent transducers. These specifications are presented in a modular way, and composing the resultant machines simulates the full specification. An important result by Dartois et al. [Luc Dartois et al., 2017] shows that composition of two-way transducers enjoy a polynomial composition when the underlying transducer is reversible, that is, if they are both deterministic and co-deterministic. This is a major improvement over general deterministic two-way transducers, for which composition causes a doubly exponential blow-up in the size of the inputs in general. Moreover, they show that reversible two-way transducers have the same expressiveness as deterministic two-way transducers. However, the notion of reversible two-way transducers over infinite words as well as the question of their expressiveness were not studied yet. In this article, we introduce the class of reversible two-way transducers over infinite words and show that they enjoy the same expressive power as deterministic two-way transducers over infinite words. This is done through a non-trivial, effective construction inducing a single exponential blow-up in the set of states. Further, we also prove that composing two reversible two-way transducers over infinite words incurs only a polynomial complexity, thereby providing an efficient procedure for composition of transducers over infinite words.
@InProceedings{dartois_et_al:LIPIcs.CONCUR.2024.21,
author = {Dartois, Luc and Gastin, Paul and Germerie Guizouarn, Lo\"{i}c and Govind, R. and Krishna, Shankaranarayanan},
title = {{Reversible Transducers over Infinite Words}},
booktitle = {35th International Conference on Concurrency Theory (CONCUR 2024)},
pages = {21:1--21:22},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-339-3},
ISSN = {1868-8969},
year = {2024},
volume = {311},
editor = {Majumdar, Rupak and Silva, Alexandra},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2024.21},
URN = {urn:nbn:de:0030-drops-207932},
doi = {10.4230/LIPIcs.CONCUR.2024.21},
annote = {Keywords: Transducers, Regular functions, Reversibility, Composition, SSTs}
}