Preferences and nonmonotonic reasoning

Gerhard Brewka, Ilkka Niemelä, Miroslaw Truszczyński

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


We give an overview of the multifaceted relationship between nonmonotonic logics and preferences. We discuss how the nonmonotonicity of reasoning itself is closely tied to preferences reasoners have on models of the world or, as we often say here, possible belief sets. Selecting extended logic programming with answer-set semantics as a generic nonmonotonic logic, we show how that logic defines preferred belief sets and how preferred belief sets allow us to represent and interpret normative statements. Conflicts among program rules (more generally, defaults) give rise to alternative preferred belief sets. We discuss how such conflicts can be resolved based on implicit specificity or on explicit rankings of defaults. Finally, we comment on formalisms that explicitly represent preferences on properties of belief sets. Such formalisms either build preference information directly into rules and modify the semantics of the logic appropriately or specify preferences on belief sets independently of the mechanism to define them.

Original languageEnglish
Pages (from-to)69-78
Number of pages10
JournalAI Magazine
Issue number4
StatePublished - 2008

ASJC Scopus subject areas

  • Artificial Intelligence


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