{"type":"ScholarlyArticle","title":"Computational Complexity of Planning and Approximate Planning in Presence of Incompleteness","authors":[{"name":"Chitta Baral","slug":"chitta-baral","given":"Chitta","family":"Baral","affiliation":""},{"name":"Vladik Kreinovich","slug":"vladik-kreinovich","given":"Vladik","family":"Kreinovich","affiliation":""},{"name":"Raul Trejo","slug":"raul-trejo","given":"Raul","family":"Trejo","affiliation":""}],"abstract":"In t he last several yea rs th e co mputational complexity of classical planning and HTN planning have b ee n s tudi ed . But in both cases it is assumed that the planner has complete knowledge about th e initial state. Recently, th ere has b ee n proposal to use 'sensing ' actions to plan in presence of incompleteness . In this paper we study the complexity of planning in such cases. In our study we use the action description language A proposed in 1993 by M. Gelfond and V. Lifschitz and its extensions. The language A allows planning in the situations with complete information. It is known t h at, if we consider only plans of feasible (polynomial) length , the planning problem for such situations is NP-complete : even checking whether a given objective is attainable from a g iv en initi al state is NP- complete. In this paper, we show that th e planning problem in presen ce of incompleteness is indeed hard er : it belongs to the next level of complexity hierarchy (in precise terms, it is I:2P-complete) . To overcome th e complexity of this problem, C. Baral and T . Son have proposed several approximations. We show that under certain conditions, one of th ese approximations - 0-approximation - mak es the problem NP- complete (thus indeed redu cing its complexity).","doi":null,"url":"https://ijcai.org/proceedings/1999/135","pdf":"https://ijcai.org/proceedings/1999/0135.pdf","markdown":"https://ijcai.org/proceedings/1999/135.md","bibtex":"https://ijcai.org/proceedings/1999/bibtex/135","volume":{"slug":"1999","title":"Proceedings of the Sixteenth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 1999","url":"https://ijcai.org/proceedings/1999/","year":1999,"location":"Stockholm, Sweden","dates":"","editors":"Thomas Dean","isbn":"","publisher":"International Joint Conferences on Artificial Intelligence","doi_prefix":""},"section":"Planning and Scheduling","track":"Planning and Scheduling","number":135,"pages":{"first":948,"last":954},"keywords":[],"videos":[],"references":[],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}