 If an agent forms a specific preference as a result of some experience, further changes in her overall preference state are often necessary to regain consistency. A model of preference change can therefore be constructed as an input-output model in the same style as standard models of belief change. (Hansson 1995, Liu 2011) Changes in preference are triggered by inputs that are represented by sentences expressing new preference patterns. Hence, if the subject grows tired of her previous favourite brand of mustard, \(A\), and starts to like brand \(C\) better, then this will be represented by a change with the sentence “\(C\) is better than \(A\)”, in formal language \(C\succ A\), as an input. However, a change in which the previous preference \(A\succ C\) is replaced by the new preference \(C\succ A\) can take place in different ways. For instance, there may be a third brand \(B\) that was previously placed between \(A\) and \(C\) in the preference ordering.  The instruction to make the new preference relation satisfy \(C\succ A\) does not tell us where \(B\) should be placed in the new ordering. The new ordering may for instance be either \(C\succ A\succ B\) or \(C\succ B\succ A\). One way to deal with this is to include additional information in the input, for instance specifying which element(s) of the alternative set should be moved while the others keep their previous positions. In our example, if only \(C\) is going to be moved, then the outcome should satisfy \(C\succ A\succ B\). These and other considerations make it necessary to modify the standard model of belief change in order to accommodate the subject matter of preferences.