Positional-Player Games

In reactive synthesis, we transform a specification to a system that satisfies the specification in all environments. For specifications in linear-temporal logic, research on bounded synthesis, where the sizes of the system and the environment are bounded, captures realistic settings and has lead to algorithms of improved complexity and implementability. In the game-based approach to synthesis, the system and its environment are modeled by strategies in a two-player game with an ω-regular objective, induced by the specification. There, bounded synthesis corresponds to bounding the memory of the strategies of the players. The memory requirement for various objectives has been extensively studied. In particular, researchers have identified positional objectives, where the winning player can follow a memoryless strategy - one that needs no memory. In this work we study bounded synthesis in the game setting. Specifically, we define and study positional-player games, in which one or both players are restricted to memoryless strategies, which correspond to non-intrusive control in various applications. We study positional-player games with Rabin, Streett, and Muller objectives, as well as with weighted multiple Büchi and reachability objectives. Our contribution covers their theoretical properties as well as a complete picture of the complexity of deciding the game in the various settings.