Transducers constitute a fundamental extension of automata. The class of regular word functions has recently emerged as an important class of word-to-word functions, characterized by means of (functional, or unambiguous, or deterministic) two-way transducers, copylessstreaming string transducers, and MSO-definable graph transformations. One of the most important result in language theory is Kleene theorem, relating finite state automata and regular expressions. R. Alur, A. Freilich and M. Raghothaman have introduced (CSL-LICS '14) a set of regular function expressions and proved a similar result for regular word functions, by showing the equivalence with copyless streaming string transducers. In this paper, we propose a direct, simplified and effective translation from unambiguous two-way transducers to regular function expressions. In addition, our approach allows us to derive a subset of regular function expressions characterizing the (strict) subclass of functional sweeping transducers.
19 April 2018, 11h0012h30
Salle de réunion du bâtiment modulaire BP5 (en bas de la BU), Luminy