The performance elements of Asa prefer cases having high utility. Forgetting/deleting cases with low utility speeds up search. Additional low utility cases ("repressed" memories) can be retained for use (in a larger "augmented" casebase) by the learning element. Knowing what NOT to do is useful there.
When a vector utility is employed we prefer to delete cases from the more densely populated regions of the case vector space. Also, if a case has a single vector component that is high we prefer to retain it.