Synchronizing Data Words for Register Automata

Register automata (RAs) are finite automata extended with a finite set of registers to store and compare data. We study the concept of synchronizing data words in RAs: Does there exist a data word that sends all states of the RA to a single state? For deterministic RAs with k registers (k-DRAs), we...

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Main Authors: Shirmohammadi, M, Babari, P, Quaas, K
Format: Conference item
Published: Schloss Dagstuhl 2016
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author Shirmohammadi, M
Babari, P
Quaas, K
author_facet Shirmohammadi, M
Babari, P
Quaas, K
author_sort Shirmohammadi, M
collection OXFORD
description Register automata (RAs) are finite automata extended with a finite set of registers to store and compare data. We study the concept of synchronizing data words in RAs: Does there exist a data word that sends all states of the RA to a single state? For deterministic RAs with k registers (k-DRAs), we prove that inputting data words with 2k+1 distinct data, from the infinite data domain, is sufficient to synchronize. We show that the synchronizing problem for DRAs is in general PSPACE-complete, and is NLOGSPACE-complete for 1-DRAs. For nondeterministic RAs (NRAs), we show that Ackermann(n) distinct data (where n is the size of RA) might be necessary to synchronize. The synchronizing problem for NRAs is in general undecidable, however, we establish Ackermann-completeness of the problem for 1-NRAs. Our most substantial achievement is proving NEXPTIME-completeness of the length-bounded synchronizing problem in NRAs (length encoded in binary). A variant of this last construction allows to prove that the bounded universality problem in NRAs is co-NEXPTIME-complete.
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spelling oxford-uuid:9d2637df-d69f-47ba-a439-82b038694fbe2022-03-27T00:40:52ZSynchronizing Data Words for Register AutomataConference itemhttp://purl.org/coar/resource_type/c_5794uuid:9d2637df-d69f-47ba-a439-82b038694fbeSymplectic Elements at OxfordSchloss Dagstuhl2016Shirmohammadi, MBabari, PQuaas, KRegister automata (RAs) are finite automata extended with a finite set of registers to store and compare data. We study the concept of synchronizing data words in RAs: Does there exist a data word that sends all states of the RA to a single state? For deterministic RAs with k registers (k-DRAs), we prove that inputting data words with 2k+1 distinct data, from the infinite data domain, is sufficient to synchronize. We show that the synchronizing problem for DRAs is in general PSPACE-complete, and is NLOGSPACE-complete for 1-DRAs. For nondeterministic RAs (NRAs), we show that Ackermann(n) distinct data (where n is the size of RA) might be necessary to synchronize. The synchronizing problem for NRAs is in general undecidable, however, we establish Ackermann-completeness of the problem for 1-NRAs. Our most substantial achievement is proving NEXPTIME-completeness of the length-bounded synchronizing problem in NRAs (length encoded in binary). A variant of this last construction allows to prove that the bounded universality problem in NRAs is co-NEXPTIME-complete.
spellingShingle Shirmohammadi, M
Babari, P
Quaas, K
Synchronizing Data Words for Register Automata
title Synchronizing Data Words for Register Automata
title_full Synchronizing Data Words for Register Automata
title_fullStr Synchronizing Data Words for Register Automata
title_full_unstemmed Synchronizing Data Words for Register Automata
title_short Synchronizing Data Words for Register Automata
title_sort synchronizing data words for register automata
work_keys_str_mv AT shirmohammadim synchronizingdatawordsforregisterautomata
AT babarip synchronizingdatawordsforregisterautomata
AT quaask synchronizingdatawordsforregisterautomata