The closed world assumption is the presumption that what is not currently known to be true is false. The same name also refers to a logical formalization of this assumption by Raymond Reiter.

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  • The closed world assumption is the presumption that what is not currently known to be true is false. The same name also refers to a logical formalization of this assumption by Raymond Reiter. The opposite of the closed world assumption is the open world assumption, stating that lack of knowledge does not imply falsity. Negation as failure is related to the closed world assumption, as it amounts to believe false every predicate that cannot be proved to be true. In the knowledge management arena, the closed world assumption is used in at least two situations: 1 when the knowledge base is known to be complete (e.g., a corporate database containing records for every employee), and 2) when the knowledge base is known to be incomplete but a "best" definite answer must be derived from incomplete information. For example, if a database contains the following table reporting editors who have worked on a given article, a query on the people not having edited the article on Formal Logic is usually expected to return “Sarah Johnson”. In the closed world assumption, the table is assumed to be complete (it lists all editor-article relationships), and Sarah Johnson is the only editor who has not edited the article on Formal Logic. In contrast, with the open world assumption the table is not assumed to contain all editor-article tuples, and the answer to who has not edited the Formal Logic article is unknown. There is an unknown number of editors not listed in the table, and an unknown number of articles edited by Sarah Johnson that are also not listed in the table. (en)
  • Die Closed-world-assumption (dt. Annahme zur Weltabgeschlossenheit) bei der Modellierung von Sachverhalten sagt aus, das alles, was nicht explizit als wahr bewiesen werden kann, als falsch bezeichnet wird: Alles was also nicht modelliert ist, existiert im Modell auch nicht und ist nicht beweisbar, also falsch, das heißt nicht ableitbar. In der Prädikatenlogik gilt diese Annahme nicht. (de)
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  • The closed world assumption is the presumption that what is not currently known to be true is false. The same name also refers to a logical formalization of this assumption by Raymond Reiter. (en)
  • Die Closed-world-assumption (dt. Annahme zur Weltabgeschlossenheit) bei der Modellierung von Sachverhalten sagt aus, das alles, was nicht explizit als wahr bewiesen werden kann, als falsch bezeichnet wird: Alles was also nicht modelliert ist, existiert im Modell auch nicht und ist nicht beweisbar, also falsch, das heißt nicht ableitbar. (de)
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  • Closed world assumption (en)
  • 閉世界仮説 (ja)
  • Closed world assumption (de)
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