Untwisting two-way transducers in elementary time
Formal Languages and Automata Theory
2017-01-11 v1
Abstract
Functional transductions realized by two-way transducers (equivalently, by streaming transducers and by MSO transductions) are the natural and standard notion of "regular" mappings from words to words. It was shown recently (LICS'13) that it is decidable if such a transduction can be implemented by some one-way transducer, but the given algorithm has non-elementary complexity. We provide an algorithm of different flavor solving the above question, that has double exponential space complexity. We further apply our technique to decide whether the transduction realized by a two-way transducer can be implemented by a sweeping transducer, with either known or unknown number of passes.
Cite
@article{arxiv.1701.02502,
title = {Untwisting two-way transducers in elementary time},
author = {Félix Baschenis and Olivier Gauwin and Anca Muscholl and Gabriele Puppis},
journal= {arXiv preprint arXiv:1701.02502},
year = {2017}
}