{"type":"ScholarlyArticle","title":"How Hard to Tell? Complexity of Belief Manipulation Through Propositional Announcements","authors":[{"name":"Thomas Eiter","slug":"thomas-eiter","given":"Thomas","family":"Eiter","affiliation":""},{"name":"Aaron Hunter","slug":"aaron-hunter","given":"Aaron","family":"Hunter","affiliation":""},{"name":"Francois Schwarzentruber","slug":"francois-schwarzentruber","given":"François","family":"Schwarzentruber","affiliation":""}],"abstract":"Consider a set of agents with initial beliefs and a formal operator for incorporating new information. Now suppose that, for each agent, we have a formula that we would like them to believe.  Does there exist a single announcement that will lead all agents to believe the corresponding formula? This paper studies the problem of the existence of such an announcement in the context of model-preference definable revision operators. First, we provide two characterisation theorems for the existence of announcements: one in the general case, the other for total partial orderings. Second, we exploit the characterisation theorems to provide upper bound complexity results. Finally, we also provide matching optimal lower bounds for the Dalal and Ginsberg operators.","doi":"10.24963/ijcai.2021/257","url":"https://ijcai.org/proceedings/2021/257","pdf":"https://ijcai.org/proceedings/2021/0257.pdf","markdown":"https://ijcai.org/proceedings/2021/257.md","bibtex":"https://ijcai.org/proceedings/2021/bibtex/257","volume":{"slug":"2021","title":"Proceedings of the Thirtieth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2021","url":"https://ijcai.org/proceedings/2021/","year":2021,"location":"Montreal","dates":"19-27 August 2021","editors":"Prof. Zhi-Hua Zhou","isbn":"978-0-9992411-9-6","publisher":"International Joint Conferences on Artificial Intelligence Organization","doi_prefix":"10.24963/ijcai.2021"},"section":"Knowledge Representation and Reasoning","track":"Main Track","number":257,"pages":{"first":1866,"last":1872},"keywords":["Knowledge Representation and Reasoning: Belief Change","Knowledge Representation and Reasoning: Reasoning about Knowledge and Belief"],"videos":[],"references":[],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}