Strategies In Infinite Games Research Articles

What are "Good" Winning Strategies in Infinite Games?

What are "Good" Winning Strategies in Infinite Games?

Continuous-time stochastic games with time-bounded reachability

We study continuous-time stochastic games with time-bounded reachability objectives and time-abstract strategies. We show that each vertex in such a game has a value (i.e., an equilibrium probability), and we classify the conditions under which optimal strategies exist. Further, we show how to compute ε-optimal strategies in finite games and provide detailed complexity estimations. Moreover, we show how to compute ε-optimal strategies in infinite games with finite branching and bounded rates where the bound as well as the successors of a given state are effectively computable. Finally, we show how to compute optimal strategies in finite uniform games.

Determinization and Memoryless Winning Strategies

We show that Safra's determinization of ω -automata with Streett (strong fairness) acceptance condition also gives memoryless winning strategies in infinite games, for the player whose acceptance condition is the complement of the Streett condition. Both determinization and memorylessness are essential parts of known proofs of Rabin's tree automata complementation lemma. Also, from Safra's determinization construction, along with its memoryless winning strategy extension, a single exponential complementation of Streett tree automata follows. A different single exponential construction and proof first appeared in [N. Klarlund (1992), Progress measures, immediate determinacy, and a subset construction for tree automata, in “Proceedings, 7th IEEE Symposium on Logics in Computer Science”].