Fair Simulation Relations, Parity Games, and State Space Reduction for Büchi Automata
Fair Simulation Relations, Parity Games, and State Space Reduction for Büchi Automata
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DOI:
10.1007/3-540-48224-5_57
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发表时间:
2001-07
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通讯作者:
K. Etessami;T. Wilke;Rebecca A. Schuller
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作者:
K. Etessami;T. Wilke;Rebecca A. Schuller
We give efficient algorithms, beating or matching optimal known bounds, for computing a variety of simulation relations on the state space of a Büchi automaton. Our algorithms are derived via a unified and simple parity-game framework. This framework incorporates previously studied notions likefairanddirectsimulation, but our main motivation is state space reduction, and for this purpose we introduce a new natural notion of simulation, calleddelayedsimulation. We show that, unlike fair simulation, delayed simulation preserves the automaton language upon quotienting, and that it allows substantially better state reduction than direct simulation.We use the parity-game approach, based on a recent algorithm by Jurdzinski, to efficiently compute all the above simulation relations. In particular, we obtain anO(mn3)-time andO(mn)-space algorithm for computing both the delayed and fair simulation relations. The best prior algorithm for fair simulation requires timeO(n6) ([HKR97]).Our framework also allows one to compute bisimulations efficiently: we compute the fair bisimulation relation inO(mn3) time andO(mn) space, whereas the best prior algorithm for fair bisimulation requires timeO(n10) ([HR00]).