<![CDATA[Lec 6:Common Knowledge and Agreement]]>Common knowledge is a fundamental notion of group knowledge.

Common knowledge is a necessary and sufficient condition for reaching an agreement and for coordinating actions.

Three famous illustrations:

  1. Coordinated attack.
  2. Agreeing to disagree.
  3. Simultaneous byzantine agreement.

Relation between common knowledge and agreement:

 

Formally capture the cognition:

 

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