Using swamps to improve optimal pathfinding

In a variety of domains, such as computer games and robotics, many shortest paths have to be found quickly in real time. We address the problem of quickly finding shortest paths in large known graphs. We propose a method that relies on identifying areas that tend to be searched needlessly (areas we call swamp-regions), and exploits this knowledge to improve search. The method requires storing only a few bits in memory for each node of the graph, and reduces search cost drastically, while still finding optimal paths. Our method is independent of the heuristics used in the search, and of the search algorithm. We present experimental results that support our claims, and provide an anytime algorithm for the pre-processing stage that identifies swamp-regions.