Reasoning about Action and Change: Actions with Abnormal Effects

Most of the research devoted to reasoning about action and change has been based on the assumption that each action behaves in a fixed way. More specifically, to each action A there is assigned a unique specification S describing the effects of A in terms of a state in which A is performed.1 For instance, the well-known action shoot is usually defined as making a gun unloaded and a turkey dead, provided that a gun was loaded. Accordingly, each time the action is executed in a state in which the gun is loaded, it is taken for granted that the turkey is made dead.