Improved Undecidability Results for Reachability Games on Recursive Timed Automata

Shankara Narayanan Krishna
(IIT Bombay)
Lakshmi Manasa
(IIT Bombay)
Ashutosh Trivedi
(IIT Bombay)

We study reachability games on recursive timed automata (RTA) that generalize Alur-Dill timed automata with recursive procedure invocation mechanism similar to recursive state machines. It is known that deciding the winner in reachability games on RTA is undecidable for automata with two or more clocks, while the problem is decidable for automata with only one clock. Ouaknine and Worrell recently proposed a time-bounded theory of real-time verification by claiming that restriction to bounded-time recovers decidability for several key decision problem related to real-time verification. We revisited games on recursive timed automata with time-bounded restriction in the hope of recovering decidability. However, we found that the problem still remains undecidable for recursive timed automata with three or more clocks. Using similar proof techniques we characterize a decidability frontier for a generalization of RTA to recursive stopwatch automata.

In Adriano Peron and Carla Piazza: Proceedings Fifth International Symposium on Games, Automata, Logics and Formal Verification (GandALF 2014), Verona, Italy, 10th - 12th September 2014, Electronic Proceedings in Theoretical Computer Science 161, pp. 245–259.
Published: 24th August 2014.

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