 Contraction should be successful, i.e., \(K\div p\) should not imply \(p\) (or not contain \(p\), which is the same thing if Closure is satisfied). However, it would be too much to require that \(p \not\in \Cn(K\div p)\) for all sentences \(p\), since it cannot hold if \(p\) is a tautology. The success postulate has to be conditional on \(p\) not being logically true.