Shaham, Eshed, Ariel Felner, Jingwei Chen, and Nathan Sturtevant. 2021. “The Minimal Set of States That Must Be Expanded in a Front-to-End Bidirectional Search”. Proceedings of the International Symposium on Combinatorial Search 8 (1):82-90. https://doi.org/10.1609/socs.v8i1.18426.