Position Paper: On the Impact of Direction-Selection in BAE

BAE^*, and the independently developed DIBBS, are state of-the-art bidirectional heuristic search algorithms that ex ploit heuristic consistency to efficiently prove solution op timality. Historically, BAE^* has been studied with various direction-selection policies, determining whether to expand the next state from the forward or backward search. However, some of these policies expand nodes with an f-value exceed ing the optimal solution cost, C^∗, which clearly cannot be part of any optimal solution. In this position paper, we re view direction-selection strategies in BAE^* and bidirectional search more broadly, analyzing their impact on the behavior of the search. Additionally, we present a low-overhead solu tion that prevents the expansion of nodes with f > C^∗ across all direction-selection strategies.