{"type":"ScholarlyArticle","title":"Optimally Efficient Bidirectional Search","authors":[{"name":"Eshed Shaham","slug":"eshed-shaham","given":"Eshed","family":"Shaham","affiliation":"School of Engineering and CS , Hebrew University of Jerusalem , Jerusalem , Israel"},{"name":"Ariel Felner","slug":"ariel-felner","given":"Ariel","family":"Felner","affiliation":"SISE Department , Ben-Gurion University of the Negev , Be'er Sheva , Israel"},{"name":"Nathan R. Sturtevant","slug":"nathan-r-sturtevant","given":"Nathan R.","family":"Sturtevant","affiliation":"CS Department , University of Alberta , Canada"},{"name":"Jeffrey S. Rosenschein","slug":"jeffrey-s-rosenschein","given":"Jeffrey S.","family":"Rosenschein","affiliation":"School of Engineering and CS , Hebrew University of Jerusalem , Jerusalem , Israel"}],"abstract":"A* is optimally efficient with regard to node expansions among unidirectional admissible algorithms — those that only assume that the heuristic used is admissible. This paper studies algorithms that are optimally efficient for bidirectional search algorithms. We present the Fractional MM algorithm and its sibling, the MT algorithm, which is simpler to analyze. We then develop variants of these algorithms that are optimally efficient, each under different assumptions on the information available to the algorithm.","doi":"10.24963/ijcai.2019/867","url":"https://ijcai.org/proceedings/2019/867","pdf":"https://ijcai.org/proceedings/2019/0867.pdf","markdown":"https://ijcai.org/proceedings/2019/867.md","bibtex":"https://ijcai.org/proceedings/2019/bibtex/867","volume":{"slug":"2019","title":"Proceedings of the Twenty-Eighth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2019","url":"https://ijcai.org/proceedings/2019/","year":2019,"location":"Macao","dates":"10-16 August 2019","editors":"Sarit Kraus","isbn":"978-0-9992411-4-1","publisher":"International Joint Conferences on Artificial Intelligence Organization","doi_prefix":"10.24963/ijcai.2019"},"section":"Best Sister Conferences","track":"Best Sister Conferences","number":867,"pages":{"first":6221,"last":6225},"keywords":["Heuristic Search and Game Playing: Heuristic Search"],"videos":[],"references":[{"position":1,"raw":"[Barley et al., 2018] Michael W. 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