Common knowledge with probability 1

Adam Brandenburger*, Eddie Dekel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Two people, 1 and 2, are said to have common knowledge of an event if both know it, 1 knows that 2 knows it, 2 knows that 1 knows it, 1 knows that 2 knows that 1 knows it, and so on. This paper provides a Bayesian definition of common knowledge, that is, a definition in terms of beliefs (probability measures). The main result is an equivalence between this definition and a definition in terms of the σ-fields representing 1 and 2's information. To obtain this result the conditional probabilities must be proper and the σ-fields posterior completed.

Original languageEnglish (US)
Pages (from-to)237-245
Number of pages9
JournalJournal of Mathematical Economics
Issue number3
StatePublished - 1987

ASJC Scopus subject areas

  • Economics and Econometrics
  • Applied Mathematics


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