28. The method as in claim 27 wherein said measure of intrusion is defined as a measure of separation between the boundary of said possibility region and the reference feature vector not of said selected class within said possibility region which is furthest from the boundary of said possibility region.
27. The method as in claim 22 wherein said step of selecting a number of said reference feature vectors comprises the steps of: (a) defining the maximum number of possibility regions desired; (b) defining a measure of intrusion of reference feature vectors not of said selected class within said possibility region; (c) defining a limit of intrusion of reference feature vectors not of said selected class within said possibility region; (d) generating one or more possibility regions, not to exceed said maximum number of possibility regions, such that all reference feature vectors of said selected class are contained in one or more of said possibility regions such that said limit of intrusion is not exceeded.