parid0508 | Wed, 20 Nov 2002 08:43:50
What you are saying in this is that this assertion has two distinct role types "Opposite of White" and "Opposite of Black". Similarly my brother and I are linked by two different role types "Brother of Ian" and "Brother of Martin" It is the pair of the role type and the role player that needs to be unique, not the role type itself. My conclusion is that the role type is not a distinguishing property. It is simply a property that allows you to identify sets of assertions that play a similar role in different assertion instances. The RM should not concern itself about the fact that the same role type occurs in different places. It should only concern itself with the uniqueness of role type/player pairs in specific instances.