 This identity cannot be used for belief sets. Since all inconsistent belief sets are identical, an operation ? such that \(K?p = (K+p)!\) will have the extremely implausible property that if \(\neg p_1 \in K_1\) and \(\neg p_2 \in K_2\), then \(K_1 ?p_1 = K_2 ?p_2\). However, other ways to perform semirevision on belief sets have been proposed, in particular, the following two-step process: