 A simple way to apply this recipe is David Makinson’s (1997) screened revision, in which there is a set \(X\) of potential core beliefs that are immune to revision. The belief set \(K\) should be revised by the input sentence \(p\) if \(p\) is consistent with the set \(X\cap K\) of actual core beliefs, otherwise not. The second step of screened revision is a revision of \(K\) by \(p\), but with the restriction that no element of \(X\cap K\) is allowed to be removed.