[sc34wg3] SAM issue: reification-effects

[Steve Pepper]

This is another issue in the SAM that should be aired on the mailing
list.

Occurrence in topic map:
   http://www.ontopia.net/omnigator/models/topic_complete.jsp?tm=tm-standards.xtm&id=1389

Occurrence in SAM:
   http://www.isotopicmaps.org/sam/sam-model/#reification-effects

The general question is: What is the relationship between the type of a
name, occurrence, association or association role, and the type of a topic
that reifies it?

E.g. if I reify the association of type "composed-by" between Puccini
and Tosca, should the reifying topic also be of type "composed-by"?

If so, is it an error (e.g., in XTM) if this type isn't stated explicitly
in the syntax? Or should a processor simply "add" the type "composed-by"
to whatever types the reifying topic already has? What if the type of the
reifying topic is a supertype (or subtype) of the association?

Conversely, what happens with the type of an association when it is
reified? Does the association "acquire" the type(s) of the reifying topic,
in addition to whatever type it might already have? If so, what happens
when the total number of types exceeds 1, which is all that an association
can have? And how does the type hierarchy affect this case?

It would be interesting to see if the RM as an analytic tool can throw
light on these questions.

Steve

--
Steve Pepper, Chief Executive Officer <pepper@ontopia.net>
Convenor, ISO/IEC JTC1/SC34/WG3  Editor, XTM (XML Topic Maps)
Ontopia AS, Waldemar Thranes gt. 98, N-0175 Oslo, Norway.
http://www.ontopia.net/ phone: +47-23233080 GSM: +47-90827246