[sc34wg3] TM Data Model issue: prop-subj-address-values
Kal Ahmed
sc34wg3@isotopicmaps.org
03 Nov 2003 15:40:45 +0000
On Mon, 2003-11-03 at 14:41, Graham Moore wrote:
> Kal,
>
> I'm well aware of the distinction between subj ind and subj address, what I
> was trying to get at was there is non-determinism in both aspects of
> identity assignment, primarily because comparison within the model is only
> ever done with locators.
>
>From an XTM 1.0 point of view, there is no non-determinism in the
identity conferred by a subject address, because comparison is done by
comparing locator addresses using appropriate URI equivalence rules.
However, I grant you that this is only in the normative processing rules
that you see this heuristic.
But, even if I accept that there is a degree of non-determinism in an
identity conferred by a subject address, the nature of that
non-determinism is different - that is what I'm getting at. With a
subject indicator, there is inherent non-determinism because it depends
on the human interpretation of a resource. With a subject address, the
question is whether the resources addressed are the same or not - not
whether the reader thinks that they describe the same subject. That is a
massive difference that you seem to be ignoring.
Cheers,
Kal
> gra
>
> ----------------------------------------------------------------
> Graham Moore, Ontopian moore@ontopia.net
> GSM: +47 926 82 437 http://www.ontopia.net
>
>
> -----Original Message-----
> From: sc34wg3-admin@isotopicmaps.org [mailto:sc34wg3-admin@isotopicmaps.org]
> On Behalf Of Kal Ahmed
> Sent: 03 November 2003 15:22
> To: sc34wg3@isotopicmaps.org
>
> On Mon, 2003-11-03 at 14:07, Graham Moore wrote:
> > Kal wrote:
> >
> > >> FACT: 1 topic can only represent one subject
> >
> > No, 1 topic *should* represent one subject but as we know the SLUO is
> > not achievable.
> >
>
> So we should abandon the only remaining heursitic in XTM that comes close to
> the SLUO ?
>
> > >> FACT: 1 resource is one subject
> >
> > Indeed but that doesn't matter.
> >
>
> It does when taken together with the preceding fact.
>
> > Both subject identifiers and subject addresses are means of
> > establishing identity. There is no guarentee of correctly determining
> > (when the URIs are
> > different) whether they are representing the same subject. So I think
> > the comparison is a useful one and gives good guidance as how we should
> proceed.
> >
>
> No, a subject indicator has a completely different semantic to a subject
> address. A subject indicator tells you that a resource describes the subject
> of a topic, not that it is the subject of a topic. They follow a heuristic
> which says that "well constructed and well chosen subject indicators will
> always convey exactly the same subject to the intended audience of the topic
> map" - otherwise they don't work. Subject address on the other hand says
> "the resource at this address *is* the subject".
> There is no concept of interpretation of the resource in the semantic of
> subject address. The only similarity is that both properties use locators.
> Thats it. They use locators in different ways with the addressed resources
> have different relationships to the subject - so I don't see how any useful
> comparison can be made.
>
> Cheers,
>
> Kal
>
>
> > ----------------------------------------------------------------
> > Graham Moore, Ontopian moore@ontopia.net
> > GSM: +47 926 82 437 http://www.ontopia.net
> >
> >
> > -----Original Message-----
> > From: sc34wg3-admin@isotopicmaps.org
> > [mailto:sc34wg3-admin@isotopicmaps.org]
> > On Behalf Of Kal Ahmed
> > Sent: 03 November 2003 14:54
> > To: sc34wg3@isotopicmaps.org
> >
> > On Mon, 2003-11-03 at 10:39, Graham Moore wrote:
> > > Ok, heres my take:
> > >
> > > FACT: 2 different URIs can reference the same resource.
> > >
> > > When merging topics based on, for example subject identifiers, the
> > > current draft states that it is an exception if the topics being
> > > merged have different values in the subject address property. From
> > > above it follows that this is an unsafe assumption. Thus to support
> > > this fact, this non-determinism, subject address should be a collection.
> > >
> >
> > FACT: 1 topic can only represent one subject
> > FACT: 1 resource is one subject
> >
> > So I think you have an even worse conflict if you let subject address
> > be a collection.
> >
> > > Let me also position things in terms of a more general principle
> > > taken from the use and expectations of subject identifiers. There is
> > > no reason why two subject identifiers cannot indicate the same
> > > subject via different indicators. It is desirable to have one and
> > > only one, but that is unlikely no matter how hard we try. But we
> > > dont say in the standard that to have two subject indicators is an
> > > error. i.e. we err on the side of flexibility because we can't be
> > > sure. If two topics are merged because a name match has triggered it
> > > or some application code has triggered it then we dont throw an
> > > exception if the two topics have different subject identifiers because
> thats the way it works.
> > > Thus, I dont see a big distinction between supporting a scheme we
> > > have defined (Subj Inds) and a scheme that exists
> > > (URI) as being different when in both cases there is a degree of
> > > ambiguity/ flexibility.
> > >
> >
> > I think you are comparing apples and oranges here. Subject indicators
> > are URIs of resources that describe subjects, and a subject can be
> > *described* by many resources. So there is, in my mind, no parallel
> > here at all.
> >
> > Cheers,
> >
> > Kal
> > --
> > Kal Ahmed, Techquila
> > Standards-based Information Management
> > e: kal@techquila.com
> > w: www.techquila.com
> > p: +44 7968 529531
> >
> > _______________________________________________
> > sc34wg3 mailing list
> > sc34wg3@isotopicmaps.org
> > http://www.isotopicmaps.org/mailman/listinfo/sc34wg3
> >
> > _______________________________________________
> > sc34wg3 mailing list
> > sc34wg3@isotopicmaps.org
> > http://www.isotopicmaps.org/mailman/listinfo/sc34wg3
> --
> Kal Ahmed <kal@techquila.com>
> techquila
>
> _______________________________________________
> sc34wg3 mailing list
> sc34wg3@isotopicmaps.org
> http://www.isotopicmaps.org/mailman/listinfo/sc34wg3
>
> _______________________________________________
> sc34wg3 mailing list
> sc34wg3@isotopicmaps.org
> http://www.isotopicmaps.org/mailman/listinfo/sc34wg3
--
Kal Ahmed <kal@techquila.com>
techquila