[sc34wg3] Association items

[Nikita Ogievetsky]

Lars,

! How can you make jan an instance of the class of all
! inquisitive people, using a class-instance association, without making
! a topic type for that class?

Not in the "instance-of" PSI, although it translates to it. For example:

<association>
   <instanceOf>
       <topicRef xlink:href="#has-quality"/>
   </instanceOf>
   <member>
       <roleSpec>
         <topicRef xlink:href="#quality"/>
       </roleSpec>
       <topicRef xlink:href="#inquisitive"/>
   </member> 
   <member>
       <roleSpec>
         <topicRef xlink:href="#person"/>
       </roleSpec>
       <topicRef xlink:href="#jan"/>
   </member>
</association>

! This was always possible:
! 
!   <association>
!     <instanceOf>
!       <topicRef xlink:href="#is-inquisitive"/>
!     </instanceOf>
! 
!     <member>
!       <roleSpec>
!         <topicRef xlink:href="#person"/>
!       </roleSpec>
!       <topicRef xlink:href="#jan"/>
!     </member>
!   </association>
! 
! Or did I misunderstand your question?

I was running out as I typed: not sure myself what I meant :-)

In any case, I think that real case for unary associations is in the data
gathering exercise, rather then in data modeling. 

On the other hand, here is a brief summary of my understanding of the
confusion related to this subject:

Some people believe that there is no such thing as an "invalid topic map".
Like there is no such think as an "invalid opinion".

Others believe that topic maps should compete with RDF as an
inference-enabling technology.

For some people associations mean "typed" sets, and as sets they can be
empty or unary.

For others associations are typed relationships and so there are should be
2+ related "things"/"subjects"/"players".

Regards,

--Nikita