{"type":"ScholarlyArticle","title":"Front-to-Front Heuristic Search for Satisficing Classical Planning","authors":[{"name":"Ryo Kuroiwa","slug":"ryo-kuroiwa","given":"Ryo","family":"Kuroiwa","affiliation":"Graduate School of Arts and Sciences , The University of Tokyo"},{"name":"Alex Fukunaga","slug":"alex-fukunaga","given":"Alex","family":"Fukunaga","affiliation":"Graduate School of Arts and Sciences , The University of Tokyo"}],"abstract":"Although symbolic bidirectional search is successful in optimal classical planning, state-of-the-art satisficing planners do not use bidirectional search. Previous bidirectional search planners for satisficing planning behaved similarly to a trivial portfolio, which independently executes forward and backward search without the desired ``meet-in-the-middle'' behavior of bidirectional search where the forward and backward search frontiers intersect at some point relatively far from the forward and backward start states. In this paper, we propose Top-to-Top Bidirectional Search (TTBS), a new bidirectional search strategy with front-to-front heuristic evaluation. We show that TTBS strongly exhibits ``meet-in-the-middle'' behavior and can solve instances solved by neither forward nor backward search on a number of domains.","doi":"10.24963/ijcai.2020/567","url":"https://ijcai.org/proceedings/2020/567","pdf":"https://ijcai.org/proceedings/2020/0567.pdf","markdown":"https://ijcai.org/proceedings/2020/567.md","bibtex":"https://ijcai.org/proceedings/2020/bibtex/567","volume":{"slug":"2020","title":"Proceedings of the Twenty-Ninth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2020","url":"https://ijcai.org/proceedings/2020/","year":2020,"location":"Yokohama","dates":"January 2021 (postponed from 11-17 July 2020)","editors":"Christian Bessiere","isbn":"978-0-9992411-6-5","publisher":"International Joint Conferences on Artificial Intelligence Organization","doi_prefix":"10.24963/ijcai.2020"},"section":"Planning and Scheduling","track":"Main track","number":567,"pages":{"first":4098,"last":4105},"keywords":["Planning and Scheduling: Planning Algorithms","Planning and Scheduling: Search in Planning and Scheduling","Planning and Scheduling: Planning and Scheduling"],"videos":[{"label":"Video","url":"https://videos.ijcai20.org/24754/file_24754.m3u8","length_sec":263,"provider":"hls"}],"references":[{"position":1,"raw":"[Alcázar et al., 2013] Vidal Alcázar, Daniel Borrajo, Susana Fernández, and Raquel Fuentetaja. 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