What if some of those user-defined relationship
types are supposed to confer subjects on some of
their role players?  How do we tell when such
subjects are the same, and therefore must be
merged?  Neither 13250 nor the current SAM faces up
to the possibility:
* that a user could define an association type
whose instances determine the subjects of one or
more their role players, and
* that more than one topic may thus have conferred
upon it the same subject, and
* that therefore such topics need to be merged.