[topicmapmail] PSIs?

[Murray Altheim]

Lars Marius Garshol wrote:
> * Lars Marius Garshol
> |
> |   a) there is both a "sID" and a "PSI" for each subject. The subject
> |      identifier always resolves to the subject indicator, so it's
> |      difficult to see how the "PSI" in this document can claim to be a
> |      PSI. Or do you define two equivalent subject identifiers for each
> |      subject?
> 
> * Murray Altheim
> | 
> | Both are considered subject identifiers. 
> 
> In that case we have a problem. Which one am I supposed to use in my
> topic maps/schemas? And which one is validation software going to look
> for? What happens if I use one and you use the other? Indeed, why have
> two at all?

Okay, I can certainly state that the "PSI" URLs are the ones to use,
since they point to the XTM document. If you've included that topic
map (datatypes.xtm) in your system, it shouldn't matter, eh? The PSI
in datatypes.xtm has subject identity with the XSD sID. But as a
matter of record I can recommend using the PSIs in the topic map
supplied with the spec.

> Note also what the PubSubj TC document says:
> 
>   "A Published Subject Indicator must explicitly state the unique URI
>   that is to be used as its Published Subject Identifier."
>             <URL: http://www.ontopia.net/tmp/pubsubj-gentle-intro.htm >
> 
> | The basis of each comes from the original XSD Recommendation, each
> | then reified as a topic in an XTM document. I thought it would be
> | strange to additionally have each of the topics also include a
> | reference to themselves as subject identifiers. That kind of
> | semantic recursion is weird.
> 
> Why not make the <subjectIndicatorRef/> in the XTM document point to
> the URI derived from the XSD Recommendation? Then you have no loop,
> and everything should be fine. You can have a single URI and simplify
> your document quite a bit.

Well, that's how it actually is right now. I only included the sID
references in the spec because they point into the XSD spec (by HTML
ID) to the specific description for each subject.

> | The <topic> elements *are* the central place where all topic
> | characteristics come together. I don't think one wants a reference
> | to itself to be included in those characteristics, and the XTM
> | document creates the set of IDs that are the PSIs.
> 
> Well, if those are the PSIs I think you should take away the XSD
> URIs. Note also that for those to be the PSIs would not be in line
> with what OASIS is recommending.

I wouldn't want to do that, since the XSD spec is *semantically*
the canonical definition for what these PSIs mean.

I think all this is resolved by (as you say) simply stating that
within topic map environments, the "PSIs" as listed are the ones
to use. The "sID" are noted as being subject identifiers within
the topic map and as links to definitions, but shouldn't be used
(but could be if the datatypes.xtm is brought into a system of
maps).

I gotta run, so I'll deal with the rest of this on Monday.

thanks!

Murray

......................................................................
Murray Altheim                  <http://kmi.open.ac.uk/people/murray/>
Knowledge Media Institute
The Open University, Milton Keynes, Bucks, MK7 6AA, UK

    Hunt the Boeing! And test your perceptions!
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