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RE : RE : Remarks on OWL Guide and question about AS&S

From: Antoine Isaac <aisaac@ina.fr>
Date: Mon, 5 May 2003 12:10:31 +0200
To: "'Smith, Michael K'" <michael.smith@eds.com>, <public-webont-comments@w3.org>
Message-ID: <000901c312ee$8fc143f0$4ff0010a@matisse>



> -----Message d'origine-----
> De : public-webont-comments-request@w3.org 
> [mailto:public-webont-comments-request@w3.org] De la part de 
> Smith, Michael K
> Envoyé : jeudi 1 mai 2003 00:32
> À : Antoine Isaac; Smith, Michael K; public-webont-comments@w3.org
> Objet : RE: RE : Remarks on OWL Guide and question about AS&S
> 
> 
> 
> Antoine,
> 
> Thanks for your further comments. As before, I have tried
> to either answer your questions or propose an editorial change 
> that I think addresses them.
> 
> 
> Antoine,
> 
> Thanks for your further comments. As before, I have tried
> to either answer your questions or propose an editorial change 
> that I think addresses them.

Mike,

Sorry for answering quite late (hmmm, May long-lasting week-ends...).
However, it is not very important, since you have almost closed the issue.

> > 
> > > > -> sections 3.2.2 and 3.2.3
> > > > 
> 
> > OK. It is just like if we tried to assert
> > 
> > <CabernetSauvignon 
> rdf:ID="SantaCruzMountainVineyardCabernetSauvignon" >
> >   <locatedIn>SantaCruzMountainsRegion</locatedIn>  
> >   <hasMaker>SantaCruzMountainVineyard</hasMaker>   
> > </CabernetSauvignon>
> > 
> > without "rdf:ressource=" pointing towards already-defined 
> ressources, 
> > or without "real" inserted OWL instance definitions. Isn't 
> it ? With 
> > such an assertion, a system couldn't infer that those 
> literals are the 
> > names of a Region and a Wineyard.
> 
> You've got the idea.  Note that the example would violate the range 
> restrictions on the locatedIn and hasMaker properties, which 
> are object 
> properties.

Understood.

> 
> > > > -> section 3.3, InverseFunctionalProperty subsection
> > > > 

> > > Think of the elements of the range in an inverse 
> functional property 
> > > as defining a unique key in the database sense. 
> > > owl:InverseFunctional implies that the elements of the 
> range provide 
> > > a unique identifier for each pair contained in the property. ]
> > 
> > I finally managed to understand (and to agree with) your rewording, 
> > but it still sounds difficult. Perhaps it would be better 
> to cancel it 
> > or to exemplify it with your wines and wineries. Even if
> > 
> > [If ChateauMargotWinery producesWine ChateauMargotWhite and 
> > ChateauMargotRed, then {ChateauMargotRed} gives a key for 
> > ChateauMargotWinery, as well as {ChateauMargotWhite}, as well as 
> > {ChateauMargotWhite, ChateauMargotRed}]
> > 
> > is still confusing, at least it gives something more concrete.
> 
> Maybe the key analogy was a bad idea.  The idea of a key in 
> the database 
> sense is that it provides a unique index to a row in a table. 
> If our mapping
> 
> is (B-><A>, C-><A>), then there is no unique id for <A>. The reason I 
> changed the text to 'pairs' was to convert the previously 
> erroneous text 
> to a description supporting a mapping like (B-><A,B>, C-><A,C>).
> 
> I will just delete the paragraph.  The preceding paragraphs include
> 
>  P(y,x) and P(z,x) implies y = z 
> 
> and
> 
>  The reason is that the inverse of a functional property
>  must be inverse functional. 
> 
> with seems more than sufficient and less confusing.

I have nothing to add.

> 
> > > > I have understood that there has been lots of arguing about the
> > > > meaning of this property (I know this issue has been
> > > largely discussed
> > > > in the rdf-logic list, but I do not find the 
> thread....). Indeed I 
> > > > believed I had got it, until I saw the two last 
> paragraph of the 
> > > > subsection. In my understanding of the definitions, an 
> > > > InverseFunctionalProperty gives a key provided it has an
> > > exactly-one
> > > > cardinality restriction on its range.
> > > 
> > > Yes.  Your understanding was correct.
> > 
> > Recalling some math courses, I wondered whether "injective 
> relation" 
> > could be used, but a quick search on the net revealed that 
> people used 
> > this expression to refer to injective *functions*, thus not fitting 
> > our one-to-many inverse-functional property. Unless people turn the 
> > definition of "injective" into something like "if p(a) and p(b) are 
> > not disjoint (a and b being instances, p(a) and p(b) sets of 
> > instances, the sets of the values of property p for a and b) then 
> > a=b", "inverse functionnal" will probably remain the best 
> choice. Or 
> > something like "disjointValuedProperty", if it has not been 
> rejected 
> > by the WebOnt group yet.
> 
> Unless it is deemed truly awful, the WG is unlikely to rename 
> properties at this point.

One never knows... Well, I fully understand that point of view.

> 
> > > > -> section 3.4.2
> > > > 
> > > > [
> > > > owl:maxCardinality can be used to specify an upper
> > > > bound. owl:minCardinality can be used to specify a 
> lower bound. In
> > > > combination, the two can be used to specify a range. ]
> > > > 
> > > > Perhaps a typo : "cardinality" (or "owl:cardinality") instead of
> > > > "range" ?
> > > 
> > > I'm using range in the [n...m] sense.  Will change to "numeric 
> > > range".
> > 
> > For my humble brains it stills sound confusing. A numerical 
> function 
> > may have something called a "numeric range", but in my opinion it 
> > would still be the "owl:range" meaning (even though restrected to a 
> > set of numbers). How about using "cardinality range" ?
> 
> The trouble with 'cardinality range' is that it is a new 
> concept, within 
> OWL, that we would need to define somewhere.  I was trying to 
> reference 
> well-understood concepts from outside OWL.  I would propose 
> replacing 'range' with 'numeric interval' (thanks to Jeremy 
> Carol for this suggestion).

A numeric interval is indeed what is to be used to described an [n...m]
interval, but then it does not make sense any more in the sentence

 [owl:maxCardinality can be used to specify an upper
	bound. owl:minCardinality can be used to specify a 
	lower bound. In combination, the two can be used to specify a
*numeric interval*.
]

since we lose the fact that this interval bounds the property cardinality.
I would sugger to add "bounding the property cardinality" (or a more
suitable verb :
my english vocabulary is quite loose) at the end of your rewording.



Thank you very much for your answers. It helped me to understand some
important points.
I hope my questionning was also helpful for you.

Bye,

Antoine
Received on Monday, 5 May 2003 06:10:36 GMT

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