Switching from Bidirectional to Unidirectional Search

Recently, we showed that for traditional bidirectional search with "front-to-end" evaluations, it is not the meeting of search fronts but the cost of proving the optimality of a solution that is problematic. Using our improved understanding of the problem, we developed a new approach to improving this kind of search: switching to unidirectional search after the search frontiers meet for the first time (with the first solution found). This new approach shows improvements over previous bidirectional search approaches and (partly) also over the corresponding unidirectional search approaches in different domains. Together with a special-purpose improvement for the TSP, this approach showed better results than the standard search algorithms using the same knowledge.