History-deterministic Timed Automata

We explore the notion of history-determinism in the context of timed automata (TA) over infinite timed words. History-deterministic (HD) automata are those in which nondeterminism can be resolved on the fly, based on the run constructed thus far. History-determinism is a robust property that admits...

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Bibliographic Details
Published in:Logical methods in computer science Vol. 20, Issue 4
Main Authors: Bose, Sougata, Henzinger, Thomas A., Lehtinen, Karoliina, Schewe, Sven, Totzke, Patrick
Format: Journal Article
Language:English
Published: Logical Methods in Computer Science Association 01.10.2024
Logical Methods in Computer Science e.V
Series:Logical Methods in Computer Science
Subjects:
Computer Science
computer science - formal languages and automata theory
computer science - logic in computer science
synthesis
History-determinism
fair simulation
Good-for-games
Timed Automata
ISSN:1860-5974, 1860-5974
Online Access:Get full text
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Summary:We explore the notion of history-determinism in the context of timed automata (TA) over infinite timed words. History-deterministic (HD) automata are those in which nondeterminism can be resolved on the fly, based on the run constructed thus far. History-determinism is a robust property that admits different game-based characterisations, and HD specifications allow for game-based verification without an expensive determinization step. We show that the class of timed $\omega$-languages recognized by HD timed automata strictly extends that of deterministic ones, and is strictly included in those recognised by fully non-deterministic TA. For non-deterministic timed automata it is known that universality is already undecidable for safety/reachability TA. For history-deterministic TA with arbitrary parity acceptance, we show that timed universality, inclusion, and synthesis all remain decidable and are EXPTIME-complete. For the subclass of TA with safety or reachability acceptance, one can decide (in EXPTIME) whether such an automaton is history-deterministic. If so, it can effectively determinized without introducing new automaton states.
ISSN:1860-5974
1860-5974
DOI:10.46298/lmcs-20(4:1)2024