{"type":"ScholarlyArticle","title":"Abstraction-based Action Ordering in Planning","authors":[{"name":"Maria Fox","slug":"maria-fox","given":"Maria","family":"Fox","affiliation":"Department of Computer and Information Sciences University of Strathclyde , Glasgow , UK"},{"name":"Derek Long","slug":"derek-long","given":"Derek","family":"Long","affiliation":"Department of Computer and Information Sciences University of Strathclyde , Glasgow , UK"},{"name":"Julie Porteous","slug":"julie-porteous","given":"Julie","family":"Porteous","affiliation":"Department of Computer and Information Sciences University of Strathclyde , Glasgow , UK"}],"abstract":"Many planning problems contain collections of symmetric objects, actions and structures which render them difficult to solve efficiently. It has been shown that the detection and exploitation of symmetric structure in planning problems can dramatically reduce the size of the search space and the time taken to find a solution. We present the idea of using an abstraction of the problem domain to reveal symmetric structure and guide the navigation of the search space. We show that this is effective even in domains in which there is little accessible symmetric structure available for pruning. Proactive exploitation represents a flexible and powerful alternative to the symmetry-breaking strategies exploited in earlier work in planning and CSPs. The notion of almost symmetry is defined and results are presented showing that proactive exploitation of almost symmetry can improve the performance of a heuristic forward search planner.","doi":null,"url":"https://ijcai.org/proceedings/2005/52","pdf":"https://ijcai.org/proceedings/2005/0052.pdf","markdown":"https://ijcai.org/proceedings/2005/52.md","bibtex":"https://ijcai.org/proceedings/2005/bibtex/52","volume":{"slug":"2005","title":"Proceedings of the Nineteenth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2005","url":"https://ijcai.org/proceedings/2005/","year":2005,"location":"Edinburgh, Scotland, UK","dates":"","editors":"","isbn":"","publisher":"International Joint Conferences on Artificial Intelligence","doi_prefix":""},"section":null,"track":"","number":52,"pages":{"first":1220,"last":1224},"keywords":[],"videos":[],"references":[{"position":1,"raw":"[Audemard and Benhamou, 2002] G. Audemard and B. Ben- hamou. 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