{"type":"ScholarlyArticle","title":"Front-to-End Bidirectional Heuristic Search with Consistent Heuristics: Enumerating and Evaluating Algorithms and Bounds","authors":[{"name":"Lior Siag","slug":"lior-siag","given":"Lior","family":"Siag","affiliation":"Ben-Gurion University of the Negev"},{"name":"Shahaf Shperberg","slug":"shahaf-shperberg","given":"Shahaf","family":"Shperberg","affiliation":"Ben-Gurion University of the Negev"},{"name":"Ariel Felner","slug":"ariel-felner","given":"Ariel","family":"Felner","affiliation":"Ben-Gurion University of the Negev"},{"name":"Nathan Sturtevant","slug":"nathan-sturtevant","given":"Nathan","family":"Sturtevant","affiliation":"University of Alberta; Alberta Machine Intelligence Institute (Amii)"}],"abstract":"Recent research on bidirectional heuristic search (BiHS) is based on the must-expand pairs theory  (MEP theory), which describes which pairs of nodes must be expanded during the search to guarantee the optimality of solutions. A separate line of research in BiHS has proposed algorithms that use lower bounds that are derived from consistent heuristics during search. This paper links these two directions, providing a comprehensive unifying view and showing that both existing and novel algorithms can be derived from the MEP theory. An extended set of bounds is formulated, encompassing both previously discovered bounds and new ones. Finally, the bounds are empirically evaluated by their contribution to the efficiency of the search","doi":"10.24963/ijcai.2023/625","url":"https://ijcai.org/proceedings/2023/625","pdf":"https://ijcai.org/proceedings/2023/0625.pdf","markdown":"https://ijcai.org/proceedings/2023/625.md","bibtex":"https://ijcai.org/proceedings/2023/bibtex/625","volume":{"slug":"2023","title":"Proceedings of the Thirty-Second International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2023","url":"https://ijcai.org/proceedings/2023/","year":2023,"location":"Macao, SAR","dates":"19-25 August 2023","editors":"Edith Elkind","isbn":"978-1-956792-03-4","publisher":"International Joint Conferences on Artificial Intelligence Organization","doi_prefix":"10.24963/ijcai.2023"},"section":"Search","track":"Main Track","number":625,"pages":{"first":5631,"last":5638},"keywords":["Search: S: Heuristic search"],"videos":[],"references":[{"position":1,"raw":"[Alcázar et al., 2020] Vidal Alcázar, Patricia J. Riddle, and Mike Barley. A unifying view on individual bounds and heuristic inaccuracies in bidirectional search. In AAAI, pages 2327-2334. AAAI Press, 2020.","title":"A unifying view on individual bounds and heuristic inaccuracies in bidirectional search","authors":"Patricia J Vidal Alcázar, Mike Riddle, Barley","year":"2020","venue":"AAAI","doi":null,"url":null,"internal_url":null},{"position":2,"raw":"[Alcázar, 2021] Vidal Alcázar. The consistent case in bidi- rectional search and a bucket-to-bucket algorithm as a middle ground between front-to-end and front-to-front. In ICAPS, pages 7-15. AAAI Press, 2021.","title":"The consistent case in bidirectional search and a bucket-to-bucket algorithm as a middle ground between front-to-end and front-to-front","authors":"; Alcázar, Vidal Alcázar","year":"2021","venue":"ICAPS","doi":null,"url":null,"internal_url":null},{"position":3,"raw":"[Chen et al., 2017] Jingwei Chen, Robert C. Holte, Sandra Zilles, and Nathan R. Sturtevant. Front-to-end bidirec- tional heuristic search with near-optimal node expansions. In IJCAI, pages 489-495. ijcai.org, 2017.","title":"Front-to-end bidirectional heuristic search with near-optimal node expansions","authors":"Jingwei Chen, Robert C Holte, Sandra Zilles, Nathan R Sturtevant","year":"2017","venue":"IJCAI","doi":null,"url":null,"internal_url":"/proceedings/2017/69"},{"position":4,"raw":"[Dechter and Pearl, 1985] Rina Dechter and Judea Pearl. Generalized best-first search strategies and the optimality of A*. J. ACM, 32(3):505-536, 1985.","title":"Generalized best-first search strategies and the optimality of A","authors":"Rina Dechter, Judea Pearl","year":"1985","venue":"J. ACM","doi":null,"url":null,"internal_url":null},{"position":5,"raw":"[Demetrescu et al., 2009] Camil Demetrescu, Andrew V Goldberg, and David S Johnson. The shortest path problem: Ninth DIMACS implementation challenge, vol- ume 74. American Mathematical Soc., 2009.","title":"The shortest path problem: Ninth DIMACS implementation challenge","authors":"Camil Demetrescu, Andrew V Goldberg, David S Johnson","year":"2009","venue":null,"doi":null,"url":null,"internal_url":null},{"position":6,"raw":"[Eckerle et al., 2017] Jurgen Eckerle, Jingwei Chen, Nathan R. Sturtevant, Sandra Zilles, and Robert C. Holte. Sufficient conditions for node expansion in bidirectional heuristic search. In ICAPS, pages 79-87, 2017.","title":"Sufficient conditions for node expansion in bidirectional heuristic search","authors":"Jurgen Eckerle, Jingwei Chen, Nathan R Sturtevant, Sandra Zilles, Robert C Holte","year":"2017","venue":"ICAPS","doi":null,"url":null,"internal_url":null},{"position":7,"raw":"[Felner et al., 2004] Ariel Felner, Richard E Korf, Ram Meshulam, and Robert C Holte. Compressing pattern databases. In National Conference on Artificial Intelli- gence (AAAI-04), pages 638-643, 2004.","title":"Compressing pattern databases","authors":"Ariel Felner, Richard E Korf, Ram Meshulam, Robert C Holte","year":"2004","venue":"National Conference on Artificial Intelligence (AAAI-04)","doi":null,"url":null,"internal_url":null},{"position":8,"raw":"[Ford and Fulkerson, 1956] Lester Randolph Ford and Del- bert R Fulkerson. Maximal flow through a network. Cana- dian journal of Mathematics, 8:399-404, 1956.","title":"Lester Randolph Ford and Delbert R Fulkerson. Maximal flow through a network","authors":"Fulkerson Ford","year":"1956","venue":"Canadian journal of Mathematics","doi":null,"url":null,"internal_url":null},{"position":9,"raw":"[Hart et al., 1968] Peter E. Hart, Nils J. Nilsson, and Bertram Raphael. A formal basis for the heuristic determination of minimum cost paths. IEEE Trans. Syst. Sci. Cybern., 4(2):100-107, 1968.","title":"A formal basis for the heuristic determination of minimum cost paths","authors":"Peter E Hart, Nils J Nilsson, Bertram Raphael","year":"1968","venue":"IEEE Trans. Syst. Sci. Cybern","doi":null,"url":null,"internal_url":null},{"position":10,"raw":"[Helmert, 2010] Malte Helmert. Landmark heuristics for the pancake problem. In SoCS, pages 109-110. AAAI Press, 2010.","title":"Landmark heuristics for the pancake problem","authors":"Malte Helmert, Helmert","year":"2010","venue":"SoCS","doi":null,"url":null,"internal_url":null},{"position":11,"raw":"[Kaindl and Kainz, 1997] Hermann Kaindl and Gerhard Kainz. Bidirectional heuristic search reconsidered. J. Artif. Intell. Res., 7:283-317, 1997.","title":"Bidirectional heuristic search reconsidered","authors":"Kainz Kaindl, Hermann Kaindl, Gerhard Kainz","year":"1997","venue":"J. Artif. Intell. Res","doi":null,"url":null,"internal_url":null},{"position":12,"raw":"[Konig, 1931] Dénes Konig. Graphok es matrixok (hungar- ian)[graphs and matrices]. Matematikai és Fizikai Lapok, 38:116-119, 1931.","title":"Graphok es matrixok (hungarian)[graphs and matrices","authors":"Dénes Konig","year":"1931","venue":"Matematikai és Fizikai Lapok","doi":null,"url":null,"internal_url":null},{"position":13,"raw":"[Korf, 1985] Richard E. Korf. Depth-first iterative- deepening: An optimal admissible tree search. Artif. In- tell., 27(1):97-109, 1985.","title":"Depth-first iterativedeepening: An optimal admissible tree search","authors":"Richard E Korf","year":"1985","venue":"Artif. Intell","doi":null,"url":null,"internal_url":null},{"position":14,"raw":"[Papadimitriou and Steiglitz, 1998] Christos H Papadim- itriou and Kenneth Steiglitz. Combinatorial optimization: algorithms and complexity. Courier Corporation, 1998.","title":"Combinatorial optimization: algorithms and complexity","authors":"Steiglitz Papadimitriou","year":"1998","venue":null,"doi":null,"url":null,"internal_url":null},{"position":15,"raw":"[Pohl, 1971] Ira Pohl. Bi-directional search. In B. Meltzer and D. Michie, editors, Machine Intelligence, volume 6, pages 127-140. Edinburgh University Press, 1971.","title":"Bi-directional search","authors":"Ira Pohl","year":"1971","venue":"Machine Intelligence","doi":null,"url":null,"internal_url":null},{"position":16,"raw":"[Sadhukhan, 2012] Samir K. Sadhukhan. A new approach to bidirectional heuristic search using error functions. In CSI, 2012.","title":"A new approach to bidirectional heuristic search using error functions","authors":"K Samir, Sadhukhan","year":"2012","venue":"CSI","doi":null,"url":null,"internal_url":null},{"position":17,"raw":"[Sewell and Jacobson, 2021] Edward C. Sewell and Shel- don H. Jacobson. Dynamically improved bounds bidirec- tional search. Artif. Intell., 291:103405, 2021.","title":"Dynamically improved bounds bidirectional search","authors":"Edward C Sewell, Sheldon H Jacobson","year":"2021","venue":"Artif. Intell","doi":null,"url":null,"internal_url":null},{"position":18,"raw":"[Shaham et al., 2017] Eshed Shaham, Ariel Felner, Jingwei Chen, and Nathan R. Sturtevant. The minimal set of states that must be expanded in a front-to-end bidirectional search. In SoCS, pages 82-90, 2017.","title":"The minimal set of states that must be expanded in a front-to-end bidirectional search","authors":"Eshed Shaham, Ariel Felner, Jingwei Chen, Nathan R Sturtevant","year":"2017","venue":"SoCS","doi":null,"url":null,"internal_url":null},{"position":19,"raw":"[Shaham et al., 2018] Eshed Shaham, Ariel Felner, Nathan R. Sturtevant, and Jeffrey S. Rosenschein. Minimizing node expansions in bidirectional search with consistent heuristics. In SoCS, pages 81-98. AAAI Press, 2018.","title":"Minimizing node expansions in bidirectional search with consistent heuristics","authors":"Eshed Shaham, Ariel Felner, Nathan R Sturtevant, Jeffrey S Rosenschein","year":"2018","venue":"SoCS","doi":null,"url":null,"internal_url":null},{"position":20,"raw":"[Shperberg et al., 2019a] Shahaf S. Shperberg, Ariel Felner, Solomon Eyal Shimony, Nathan R. Sturtevant, and Avi Hayoun. Improving bidirectional heuristic search by bounds propagation. In SoCS, pages 106-114, 2019.","title":"Improving bidirectional heuristic search by bounds propagation","authors":"Shperberg","year":"2019","venue":"SoCS","doi":null,"url":null,"internal_url":null},{"position":21,"raw":"[Shperberg et al., 2019b] Shahaf S. Shperberg, Ariel Felner, Nathan R. Sturtevant, Solomon Eyal Shimony, and Avi Hayoun. Enriching non-parametric bidirectional search al- gorithms. In AAAI, pages 2379-2386. AAAI Press, 2019.","title":"Enriching non-parametric bidirectional search algorithms","authors":"Shperberg","year":"2019","venue":"AAAI","doi":null,"url":null,"internal_url":null},{"position":22,"raw":"[Shperberg et al., 2021] Shahaf S. Shperberg, Steven Dani- shevski, Ariel Felner, and Nathan R. Sturtevant. Iterative- deepening bidirectional heuristic search with restricted memory. In ICAPS, pages 331-339. AAAI Press, 2021.","title":"Iterativedeepening bidirectional heuristic search with restricted memory","authors":"S Shahaf, Steven Shperberg, Ariel Danishevski, Nathan R Felner, Sturtevant","year":"2021","venue":"ICAPS","doi":null,"url":null,"internal_url":null},{"position":23,"raw":"[Sturtevant et al., 2020] Nathan R. Sturtevant, Shahaf S. Sh- perberg, Ariel Felner, and Jingwei Chen. Predicting the effectiveness of bidirectional heuristic search. In ICAPS, pages 281-290. AAAI Press, 2020.","title":"Predicting the effectiveness of bidirectional heuristic search","authors":"Nathan R Sturtevant, Shahaf S Shperberg, Ariel Felner, Jingwei Chen","year":"2020","venue":"ICAPS","doi":null,"url":null,"internal_url":null},{"position":24,"raw":"[Sturtevant, 2012] Nathan R. Sturtevant. Benchmarks for grid-based pathfinding. IEEE Trans. Comput. Intell. AI Games, 4(2):144-148, 2012.","title":"Benchmarks for grid-based pathfinding","authors":"Nathan R Sturtevant","year":"2012","venue":"IEEE Trans. Comput. Intell. AI Games","doi":null,"url":null,"internal_url":null}],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}