Agreeing on Decisions

Robert J. Aumann and Sergiu Hart

(Acrobat PDF file)

Short Abstract
A coherent formalization of the Decision Agreement Theorem.

Long Abstract
The Decision Agreement Principle, originally promulgated by Cave and Bacharach (independently), asserts that if like-minded decision makers commonly know each other's decisions, then the decisions are the same. Subsequently, Moses and Nachum discovered a flaw in the reasoning underlying the principle. Here we provide a careful, coherent, and correct formulation of the principle, which avoids the Moses-Nachum flaw, and enables us to understand just when the principle applies, and when it doesn't.


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© Sergiu Hart