 It remains to specify the qualitative revision operation. Lin and Kelly adopt an operation proposed by Shoham (1987). The plausibility order \(\prec\) is updated on evidence \(E\) by setting every answer incompatible with \(E\) to be strictly less plausible than every answer compatible with \(E,\) and otherwise leaving the order unchanged. Let \(\prec_E\) denote the result of this update operation. We use the updated plausibility order to define a belief revision rule by setting \(\Bel_E = \Bel_{\prec_E}.\) Then, for all \(E,F\subseteq W\), \(B_E\) is deductively cogent and satisfies: