Re: An occurrence example. (was: Re: [xtm-wg] ANNOUNCE: Update of XTM Repository (new XTM prototype DTD))

["Steven R. Newcomb" <srn@coolheads.com>]

> > [Kal Ahmed:]
> > > ... what is the meaning of this ?
> > >
> > > <topic>
> > > 	<baseName>techquila.com</baseName>
> > > 	<occurrences>
> > > 		<resource>
> > > 			<scope>
> > > 				<topicRef xlink:href="#some-topic"/>
> > > 			</scope>
> > > 			<topicRef
> > xlink:href="http://www.techquila.com/" referent="isSubject"/>
> > > 		</resource>
> > > 	</occurrences>
> > > </topic>
> >
> [SRN]
> > It means two things:
> >
> > (1) The subject of this topic is the information found at
> >     http://www.techquila.com.  (Not what that information describes;
> >     the information itself, because you said referent="isSubject"
> >     rather than referent="describesSubject".)  Any other <topic>s that
> >     have the same subject will be merged with this one.

[Kal Ahmed:]
> Checking my understanding here. The <scope> makes no difference. If
> I have another <topic> with the same subject contained in an
> occurrence which has a different scope, then the merge will still
> take place. Right ?

Yes.  The <scope>, as always, helps differentiate between occurrences.
But that's all in occurrence-land.  The fact that a particular
information object is a subject descriptor is scopeless; it's
absolutely true in all cases and in all situations.  Indeed, I think
the binding between topic nodes and their subject descriptors is the
most fundamental aspect of the whole idea of topic maps.

> > (2) The information found at http://www.techquila.com is an occurrence
> >     of the topic, within a scope that apparently, from your example,
> >     consists of two topic nodes:
> >
> >     (a) The topic node that corresponds to the <topic> whose address
> >         is "#some-topic".  Or, if #some-topic is not the address of a
> >         <topic>, but instead it's the address of something that's not
> >         a <topic>, then it's the topic node that is called into
> >         existence by virtue of the fact that you used a <topicRef> to
> >         point at it, whose subject is whatever the information object
> >         found at "#some-topic" describes.  (I say "describes", rather
> >         than "is", because the default value of the -referent-
> >         attribute of <topicRef> is "describesSubject", and you didn't
> >         specify a -referent- attribute on the <topicRef> in your
> >         <scope> element.)
> >
> >     (b) The topic node that corresponds to the XTM-defined subject,
> >         "subject descriptor is subject".  (Not the XTM-defined
> >         subject, "subject descriptor describes subject", because you
> >         said referent="isSubject", rather than
> >         referent="describesSubject".)

> OK - I didn't appreciate the full identity/occurrence duality here.

It's interesting, beautiful, clean, and minimal, I think.
Occurrence-ness is one thing, while subject-descriptor-ness is another
thing, but it doesn't make sense to have to declare a subject
descriptor twice, once as a subject descriptor, and again as an
occurrence, just so users can see it and deal with it in the usual
way, i.e., within some scope.

> I now understand what you say to mean that the subject has no scope
> but the occurrence which is used to specify the subject or subject
> descriptor does have scope and one theme (sorry for using that
> word...old habits die hard...) in that scope which has a subject
> defined in XTM.

Right.

-Steve

--
Steven R. Newcomb, Consultant
srn@coolheads.com

voice: +1 972 359 8160
fax:   +1 972 359 0270

405 Flagler Court
Allen, Texas 75013-2821 USA

-------------------------- eGroups Sponsor -------------------------~-~>
Create your business web site your way now at Bigstep.com.
It's the fast, easy way to get online, to promote your business,
and to sell your products and services. Try Bigstep.com now.
http://click.egroups.com/1/9183/1/_/337252/_/973744930/
---------------------------------------------------------------------_->

To Post a message, send it to:   xtm-wg@eGroups.com

To Unsubscribe, send a blank message to: xtm-wg-unsubscribe@eGroups.com