Type-WA*: Using Exploration in Bounded Suboptimal Planning

Type-WA*: Using Exploration in Bounded Suboptimal Planning

Eldan Cohen, Richard Valenzano, Sheila McIlraith

Proceedings of the Thirtieth International Joint Conference on Artificial Intelligence
Main Track. Pages 4047-4053. https://doi.org/10.24963/ijcai.2021/557

Previous work on satisficing planning using greedy best-first search (GBFS) has shown that non-greedy, randomized exploration can help escape uninformative heuristic regions and solve hard problems faster. Despite their success when used with GBFS, such exploration techniques cannot be directly applied to bounded suboptimal algorithms like Weighted A* (WA*) without losing the solution-quality guarantees. In this work, we present Type-WA*, a novel bounded suboptimal planning algorithm that augments WA* with type-based exploration while still satisfying WA*'s theoretical solution-quality guarantee. Our empirical analysis shows that Type-WA* significantly increases the number of solved problems, when used in conjunction with each of three popular heuristics. Our analysis also provides insight into the runtime vs. solution cost trade-off.
Keywords:
Planning and Scheduling: Planning Algorithms
Planning and Scheduling: Search in Planning and Scheduling
Heuristic Search and Game Playing: Heuristic Search