As I was pondering the treatment of nulls in Neo4j (Null Values in Neo4j), it occurred to me that we have something quite similar in the TMDM.
The definition of association items includes this language:
[roles]: A non-empty set of association role items. The association roles for all the topics that participate in this relationship.
I read this as saying that if I don’t know their role, I can’t include a known player in an association.
For example, I am modeling an association between two players to a phone conversation, who are discussing a drone strike or terrorist attack by other means.
I know their identities but I don’t know their respective roles in relationship to each other or in the planned attack.
I want to capture this association because I may have other associations where they are players where roles are known. Perhaps enabling me to infer possible roles in this association.
Newcomb has argued roles in associations are unique and in sum, constitute the type of the association. I appreciate the subtlety and usefulness of that position but it isn’t a universal model for associations.
By the same token, the TMDM restricts associations to use where all roles are known. Given that roles are often unknown, that also isn’t a universal model for associations.
I don’t think the problem can be solved by an “unknown role” topic because that would merge unknown roles across associations.
My preference would be to allow players to appear in associations without roles.
Where the lack of a role prevents the default merging of associations. That is, all unknown roles are presumed to be unique.
Suggestions?