Most planners are based on grounding, that is, generating all instances of a parameterized action during a preprocessing phase. For some problems the number of ground actions is too high, causing a performance bottleneck. Building upon an existing approach, we present an enhanced method to split action schemas automatically during the grounding phase, to reduce the number of ground actions. First, we propose to exploit the structural knowledge of the problems to have a more informative dependency graph. Then, we suggest a better objective function to define and choose the best split. Finally, we present a more effective search to find it. We experimentally measure the impact of each of these improvements, and show that our approach significantly outperforms the state of the art.

Indirect effects of agent's actions have traditionally been formalized as condition-effect rules that always fire whenever applicable, after each action taken by the agent. In this work, we investigate a core problem of indirect effects, the possibility of arbitrarily or infinitely long sequences of rule firings. Specifically we investigate the termination of rule firings, as well as their confluence, that is, the uniqueness of the state that is ultimately reached. Both problems turn out to be PSPACE-complete. After this, we devise practically interesting syntactic and structural restrictions that guarantee polynomial-time termination and confluence tests. Finally, in the context of planning languages that support indirect effects, we propose new implementation technologies.