Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/102274
Title: Synchronizing automata over nested words
Authors: Chistikov, D.
Martyugin, P.
Shirmohammadi, M.
Issue Date: 2016
Publisher: Springer Verlag
Citation: Chistikov D. Synchronizing automata over nested words / D. Chistikov, P. Martyugin, M. Shirmohammadi. — DOI 10.1007/978-3-662-49630-5_15 // Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). — 2016. — Vol. 9634. — P. 252-268.
Abstract: We extend the concept of a synchronizing word from deterministic finite-state automata (DFA) to nested word automata (NWA): A well-matched nested word is called synchronizing if it resets the control state of any configuration, i.e., takes the NWA from all control states to a single control state. We show that although the shortest synchronizing word for an NWA, if it exists, can be (at most) exponential in the size of the NWA, the existence of such a word can still be decided in polynomial time. As our main contribution, we show that deciding the existence of a short synchronizing word (of at most given length) becomes PSPACE-complete (as opposed to NP-complete for DFA). The upper bound makes a connection to pebble games and Strahler numbers, and the lower bound goes via small-cost synchronizing words for DFA, an intermediate problem that we also show PSPACE-complete. We also characterize the complexity of a number of related problems, using the observation that the intersection nonemptiness problem for NWA is EXP-complete. © Springer-Verlag Berlin Heidelberg 2016.
Keywords: AUTOMATA THEORY
POLYNOMIAL APPROXIMATION
SYNCHRONIZATION
CONTROL STATE
DETERMINISTIC FINITE STATE AUTOMATA
LOWER BOUNDS
POLYNOMIAL-TIME
PSPACE-COMPLETE
SYNCHRONIZING AUTOMATA
SYNCHRONIZING WORDS
WORD AUTOMATA
FINITE AUTOMATA
URI: http://hdl.handle.net/10995/102274
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 84961712561
PURE ID: 738598
eb0feb23-0b0b-4ce7-baae-45ad152af027
ISSN: 3029743
ISBN: 9783662496299
DOI: 10.1007/978-3-662-49630-5_15
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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