{"type":"ScholarlyArticle","title":"Complexity Results for Planning","authors":[{"name":"Tom Bylander","slug":"tom-bylander","given":"Tom","family":"Bylander","affiliation":""}],"abstract":"I describe several computational complexity results for planning, some of which identify tractable planning problems. The model of planning, called \"propositional planning,\" is simple-conditions within operators are literals with no variables allowed . The different planning problems are defined by different restrictions on the preconditions and postconditions of operators. The main results are: Propositional planning is PSPACE-complete, even if operators are restricted to two positive (nonnegated) preconditions and two postconditions, or if operators are restricted to one postcondition (with any number of preconditions). It is NP-complete if operators are restricted to positive postconditions, even if operators are restricted to one precondition and one positive postcondition. It is tractable in a few restricted cases, one of which is if each operator is restricted to positive preconditions and one postcondition. The blocks-world problem, slightly modified, is a subproblem of this restricted planning problem.","doi":null,"url":"https://ijcai.org/proceedings/1991/41","pdf":"https://ijcai.org/proceedings/1991/0041.pdf","markdown":"https://ijcai.org/proceedings/1991/41.md","bibtex":"https://ijcai.org/proceedings/1991/bibtex/41","volume":{"slug":"1991","title":"Proceedings of the Twelfth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 1991","url":"https://ijcai.org/proceedings/1991/","year":1991,"location":"Sydney, New South Wales, Australia","dates":"24-30 August 1991","editors":"John Mylopoulos and Ray Reiter","isbn":"","publisher":"International Joint Conferences on Artificial Intelligence","doi_prefix":""},"section":"Automated Reasoning","track":"Automated Reasoning","number":41,"pages":{"first":274,"last":278},"keywords":[],"videos":[],"references":[],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}