Re: [xtm-wg] <member> question

[Steve Pepper <pepper@ontopia.net>]

At 09:50 26.04.2001 +0200, Jan Algermissen wrote:
>I have a question regarding the <member> element content:
>
><!ELEMENT member
>   ( roleSpec?, ( topicRef | resourceRef | subjectIndicatorRef )* )
>>
>
>So it is valid to have
>
><association>
>  <member>
>  </member>
></association>

Yes.

>Can anybody give me a clue how this is to
>be interpreted or what the reason is that
>this is allowed ?

The point is to allow the representation of incomplete
knowledge. Your example tells us that there is an association,
of type unknown, in which one member partakes, in an unknown
role, and that we don't know what topic plays that role.

This is the absurd example, of course. More likely ones
might be:

1.

<association>
  <instanceOf><topicRef xlink:href="#married-to"/></instanceOf>
  <member>
    <roleSpec><topicRef xlink:href="#husband"/></roleSpec>
    <topicRef xlink:href="#fred"/>
  </member>
  <member>
    <roleSpec><topicRef xlink:href="#wife"/></roleSpec>
  </member>
</association>

We know Fred is someone's husband, but don't know the identity
of the wife.

2.

<association>
  <instanceOf><topicRef xlink:href="#teacher-pupil"/></instanceOf>
  <member>
    <topicRef xlink:href="#fred"/>
  </member>
  <member>
    <topicRef xlink:href="#wilma"/>
  </member>
</association>

We know there is a teacher-pupil relationship between Fred and
Wilma, but we don't know who plays which role.

Note that this is *NOT* about permitting "incomplete" topic maps,
it is about permitting "complete" topic maps to express incomplete
knowledge.

Hope this helps.

Steve

--
Steve Pepper, Chief Technology 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


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