作者: Malte Helmert , Tor Lattimore , Levi HS Lelis , Laurent Orseau , Nathan R Sturtevant
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摘要: We tackle two long-standing problems related to re-expansions in heuristic search algorithms. For graph search, A* can require expansions, where is the number of states within the final bound. Existing algorithms that address this problem like B and B' improve this bound to . For tree search, IDA* can also require expansions. We describe a new algorithmic framework that iteratively controls an expansion budget and solution cost limit, giving rise to new graph and tree search algorithms for which the number of expansions is , where is the optimal solution cost. Our experiments show that the new algorithms are robust in scenarios where existing algorithms fail. In the case of tree search, our new algorithms have no overhead over IDA* in scenarios to which IDA* is well suited and can therefore be recommended as a general replacement for IDA*.