A Regular and Complete Notion of Delay for Streaming String Transducers

Fuente: arXiv
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Autori principali: Filiot, Emmanuel, Jecker, Ismaël, Löding, Christof, Winter, Sarah
Natura: Preprint
Pubblicazione: 2022
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author Filiot, Emmanuel
Jecker, Ismaël
Löding, Christof
Winter, Sarah
author_facet Filiot, Emmanuel
Jecker, Ismaël
Löding, Christof
Winter, Sarah
contents The notion of delay between finite transducers is a core element of numerous fundamental results of transducer theory. The goal of this work is to provide a similar notion for more complex abstract machines: we introduce a new notion of delay tailored to measure the similarity between streaming string transducers (SST). We show that our notion is regular: we design a finite automaton that can check whether the delay between any two SSTs executions is smaller than some given bound. As a consequence, our notion enjoys good decidability properties: in particular, while equivalence between non-deterministic SSTs is undecidable, we show that equivalence up to fixed delay is decidable. Moreover, we show that our notion has good completeness properties: we prove that two SSTs are equivalent if and only if they are equivalent up to some (computable) bounded delay. Together with the regularity of our delay notion, it provides an alternative proof that SSTs equivalence is decidable. Finally, the definition of our delay notion is machine-independent, as it only depends on the origin semantics of SSTs. As a corollary, the completeness result also holds for equivalent machine models such as deterministic two-way transducers, or MSO transducers.
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id arxiv_https___arxiv_org_abs_2205_04287
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle A Regular and Complete Notion of Delay for Streaming String Transducers
Filiot, Emmanuel
Jecker, Ismaël
Löding, Christof
Winter, Sarah
Formal Languages and Automata Theory
The notion of delay between finite transducers is a core element of numerous fundamental results of transducer theory. The goal of this work is to provide a similar notion for more complex abstract machines: we introduce a new notion of delay tailored to measure the similarity between streaming string transducers (SST). We show that our notion is regular: we design a finite automaton that can check whether the delay between any two SSTs executions is smaller than some given bound. As a consequence, our notion enjoys good decidability properties: in particular, while equivalence between non-deterministic SSTs is undecidable, we show that equivalence up to fixed delay is decidable. Moreover, we show that our notion has good completeness properties: we prove that two SSTs are equivalent if and only if they are equivalent up to some (computable) bounded delay. Together with the regularity of our delay notion, it provides an alternative proof that SSTs equivalence is decidable. Finally, the definition of our delay notion is machine-independent, as it only depends on the origin semantics of SSTs. As a corollary, the completeness result also holds for equivalent machine models such as deterministic two-way transducers, or MSO transducers.
title A Regular and Complete Notion of Delay for Streaming String Transducers
topic Formal Languages and Automata Theory
url https://arxiv.org/abs/2205.04287