[sc34wg3] Subjects, role players, and user-defined association types

[Lars Marius Garshol]

* Steven R. Newcomb
| 
| The SAM can define merging rules for all of the subjects that are
| yielded by the above semantics, but it can't define merging rules
| for subjects that may be yielded by user-defined association types,
| since we can't know what their semantics will be.

Well, this is no harder for the SAM than it is for the RM. I've argued
that this capability should be added to TMCL, and I still think it
ought to be.

| 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.

I don't follow you at all here. What is the SAM would have to do that
it does not in order to allow this?
 
| (3) We say that user-defined assertion types in
|     XTM/HyTM *are* allowed to have semantics such
|     that the subjects of their role players are
|     specified by instances of such user-defined
|     assertion types.  We require that, when such
|     topic maps are interchanged, they must include
|     the information necessary to allow such
|     subjects to be merged automatically, in the
|     normal course of topic map processing, whenever
|     such subjects are identical.

I prefer this one, except that I think the requirement that the
merging rules be included should be taken out. I may use occurrence
type X without using it for merging, while someone else may use it for
merging. I see nothing wrong with that, but it does mean that this
requirement becomes meaningless. It's up to the user to decide what
must be unique and what does not need to be.
 
| In any case, we really need to face this issue.  

How is this an issue? I'm afraid I don't really understand where the
problem is.

-- 
Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >