 The logic of conditionals then mirrors the logic of belief revision: (\(*\)1) corresponds to RCK, (\(*\)2) to ID, (\(*\)3) to SM, a weakened version of (\(*\)4) (viz., if \(A \in K\) and \(K\) is consistent, then \(K \subseteq K*A\)) to CS, (\(*\)6) corresponds to LLE, (\(*\)7) to OR and (\(*\)8) to RMon. In establishing this logic, Gärdenfors used the following notion of validity: a sentence \(A\) is valid in a BRM \(M\) if there is no consistent \(K\in \cK\) with \(\neg A\in K\). A sentence \(A\) is valid iff it is valid in every BRM. Arló-Costa and Levi (1996) call this notion negative validity and contrast it with a notion of positive validity that they argue is preferable: \(A\) is positively valid in a BRM \(M\) if \(A\in K\) for every \(K\in \cK\).