Suppose that \(U_i(E)\) is the event that the player \(i\) is unaware of the event \(E\). Of course, if \(i\) is unaware of \(E\) then \(i\) does not know that \(E\) is true (\(U_i(E)\subseteq \overline{K_i(E)}\), where \(\overline{X}\) denotes the complement of the event \(X\)). Recall that in epistemic models (where the players’ information is described by partitions), we have the negative introspection property: