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Re: owl:Thing and RDF

From: Ivan Herman <ivan@w3.org>
Date: Sun, 30 Oct 2005 10:43:31 +0100
Message-ID: <436495C3.1050302@w3.org>
To: Hans Teijgeler <hans.teijgeler@quicknet.nl>
Cc: "Manola, Frank" <fmanola@acm.org>, semantic-web@w3.org, "Paap, Onno" <onno.paap@ezzysurf.com>


-------- Original Message --------
From: "Hans Teijgeler" <hans.teijgeler@quicknet.nl>
To: "'Ivan Herman'" <ivan@w3.org>
CC: "Manola, Frank" <fmanola@acm.org>, semantic-web@w3.org, "Paap, Onno"
<onno.paap@ezzysurf.com>
Subject: Re:owl:Thing and RDF
Date: 30/10/2005 09:57

> Hi Ivan,
>
>
>
> Would this be acceptable:
>
> <owl:Thing rdf:ID="PHO-387392">
>
>        <rdf:type
> rdf:resource="http://www.iso15926.org/part2/2003-12#PhysicalObject"/>
>
> </owl:Thing>
>
> ?


Yes. (with one or more rdf:type statements, as you wish)

Ivan

>
>
>
> Regards,
>
> Hans
>
>
>
> PS    Then it is close to what the military do: name, rank and number. The
> number of resulting triples seems to be the same as Frank's:
>
> <iso:PhysicalObject rdf:ID="PHO-387392"/>
>
>
>
> The "Thing" solution may have an advantage for me in that for individuals
> that exist in space-time we have more than one typing to do, e.g.:
>
> <owl:Thing rdf:ID="PHO-387392">
>
>        <rdf:type
> rdf:resource="http://www.iso15926.org/part2/2003-12#PhysicalObject"/>
>
>        <rdf:type
> rdf:resource="http://www.iso15926.org/part4/2005-10#MalePerson"/>
>
> </owl:Thing>
>
>
>
> (if PHO-387392 had been myCar, then it would read:
>
> <owl:Thing rdf:ID="PHO-387392">
>
>        <rdf:type
> rdf:resource="http://www.iso15926.org/part2/2003-12#PhysicalObject"/>
>
>        <rdf:type rdf:resource="http://www.iso15926.org/part4/2005-10#Car"/>
>
> </owl:Thing>
>
> )  (where actually the identification of MalePerson and Car would read
> something like COP-436327 and COIPO-438212, where COP=ClassOfPerson and
> COIPO-ClassOfInanimatePhysicalObject)
>
>
>
>
>
>
>
> -----Original Message-----
> From: Ivan Herman [mailto:ivan@w3.org]
> Sent: Friday, October 28, 2005 3:08 PM
> To: Hans Teijgeler
> Cc: 'Frank Manola'; semantic-web@w3.org; Paap, Onno
> Subject: Re: owl:Thing and RDF
>
> -------- Original Message --------
>
> From: "Hans Teijgeler" <hans.teijgeler@quicknet.nl>
>
> To: "'Frank Manola'" <fmanola@acm.org>
>
> CC: "'Herman, Ivan'" <ivan@w3.org>, semantic-web@w3.org, "Paap, Onno"
>
> <onno.paap@ezzysurf.com>
>
> Subject: Re:owl:Thing and RDF
>
> Date: 28/10/2005 08:08
>
>
>
>
>>Thanks, Frank, it is crystal clear to me now.
>
>
>>I hope Ivan agrees.
>
>
>
>
> Yep... this is, indeed, a question of taste and readability. For outside
> user of
>
> a large RDF dataset using owl:Thing may make things (sic!) easier to read
> and
>
> comprehend. I tend to avoid to much implicit knowledge in these syntactical
>
> choices, but that may be only me.
>
>
>
> Ivan
>
>
>
>
>
>
>
>
>>Hans
>
>
>
>>===========================================
>
>
>
>>-----Original Message-----
>
>
>>From: semantic-web-request@w3.org [mailto:semantic-web-request@w3.org] On
>
>
>>Behalf Of Frank Manola
>
>
>>Sent: Thursday, October 27, 2005 11:36 PM
>
>
>>To: Hans Teijgeler
>
>
>>Cc: Herman, Ivan; semantic-web@w3.org
>
>
>>Subject: Re: owl:Thing and RDF
>
>
>
>
>>Hans--
>
>
>
>>See embedded comments below.
>
>
>
>>Hans Teijgeler wrote:
>
>
>
>>>Hi Frank and Ivan,
>
>
>
>>>Thank you for your responses!
>
>
>
>>>Two opinions, and this poor newbie must make a choice, where he had
>
>
>>>hoped for a solution:
>
>
>
>>>==========================================
>
>
>>>Ivan Herman wrote:
>
>
>
>>>I think that
>
>
>
>>>- if you use OWL Full, then owl:Thing is equivalent to rdf:Resource, you
>
>
>>>can't be more general than that:-)
>
>
>
>>>- if you use OWL DL or Lite, than you *have* to use owl:Thing, this is
>
>
>>>the way you identify individuals
>
>
>
>>>Ie: the safe bet is to use owl:Thing. You do not loose anything and, if
>
>
>>>at some point you have a smaller ontology that turns out DL or Lite,
>
>
>>>then you are all set.
>
>
>
>>>Just my personal opinion...
>
>
>
>>>Ivan
>
>
>>>=========================================
>
>
>>>Frank Manola wrote:
>
>
>
>>>Hi Hans--
>
>
>
>>>I'm probably not the most reliable guide on OWL dialects, and I'm not
>
>
>>>sure I fully understand what you're doing.  However, I don't see the
>
>
>>>need to use owl:Thing explicitly at all.  My understanding is, if you
>
>
>>>create a user-defined OWL class, e.g.,
>
>
>
>>><owl:Class rdf:ID="UserDefinedClass"/>
>
>
>
>>>or as a triple
>
>
>
>>>ex:UserDefinedClass rdf:type owl:Class  .
>
>
>
>>>then UserDefinedClass is implicitly a subclass of owl:Thing;  you need
>
>
>>>not say anything else.  Then, if you create an instance myInstance and
>
>
>>>type it as a member of that OWL class, e.g.,
>
>
>
>>>ex:myInstance rdf:type ex:UserDefinedClass  .
>
>
>
>>>then myInstance is implicitly an instance of owl:Thing.  This is true in
>
>
>>>any of the OWL dialects.
>
>
>
>>>--Frank
>
>
>>>=============================================
>
>
>
>>>Since both seem OK to me, the question arises why this is possible at
>
>
>>>all. Why has the SW been made so complex? Time for a clean-up?
>
>
>
>
>
>>I'm not sure I understand your concern.  If the problem is that there
>
>
>>are equivalent ways to say the same thing in the SW, and you expect
>
>
>>there to be only one way, I don't think that's a very realistic
>
>
>>expectation if the SW is to get anywhere expressing reasonably complex
>
>
>>things.  After all, there are certainly lots of ways to say the same
>
>
>>thing in English (or Dutch, or C), right?
>
>
>
>>>Frank, if I would follow Ivan's advice, and typically use something
>
>
>>>explicit like:
>
>
>
>>>   <owl:Thing rdf:ID="PHO-387392"/>
>
>
>>>   <owl:Thing rdf:about="#PHO-387392">
>
>
>>>       <rdf:type
>
>
>>>rdf:resource="http://www.iso15926.org/part2/2003-12#PhysicalObject"/>
>
>
>>>       <rdfs:label>Joe Blogg</rdfs:label>
>
>
>>>   </owl:Thing>
>
>
>
>>>do you see any REAL disadvantage (other than the neglect of RDF)? Given
>
>
>>>the fact that we use OWL very rigorously by superimposing the ISO
>
>
>>>15926-2 data model, clearly and consistently distinguishing individuals
>
>
>>>from classes by using owl:Thing seems to fit in that rigor (or rigour,
>
>
>>>if you want).
>
>
>
>
>
>>Perhaps I'm missing something (or I didn't explain myself very well),
>
>
>>but I don't really understand the dilemma.  Of course you can use the
>
>
>>syntax above (and I don't really think that it "neglects" RDF in any
>
>
>>awful way!).  The only possible disadvantage I see is extra syntax.
>
>
>>There is an example in Section 3.1.2 of the OWL Guide
>
>
>>(http://www.w3.org/TR/owl-guide/) that seems to exactly parallel your
>
>
>>example.  In that example, the Guide notes that, in defining an
>
>
>>instance, the syntax
>
>
>
>>   <Region rdf:ID="CentralCoastRegion" />
>
>
>
>>is exactly equivalent in meaning to
>
>
>
>>   <owl:Thing rdf:ID="CentralCoastRegion" />
>
>
>
>>   <owl:Thing rdf:about="#CentralCoastRegion">
>
>
>>      <rdf:type rdf:resource="#Region"/>
>
>
>>   </owl:Thing>
>
>
>
>>Thus it seems to me that instead of writing your example
>
>
>
>>    <owl:Thing rdf:ID="PHO-387392"/>
>
>
>
>>    <owl:Thing rdf:about="#PHO-387392">
>
>
>>       <rdf:type
>
>
>>   rdf:resource="http://www.iso15926.org/part2/2003-12#PhysicalObject"/>
>
>
>>       <rdfs:label>Joe Blogg</rdfs:label>
>
>
>>    </owl:Thing>
>
>
>
>>you could write it instead as something like:
>
>
>
>>   <iso:PhysicalObject rdf:ID="PHO-387392">
>
>
>>      <rdfs:label>Joe Blogg</rdfs:label>
>
>
>>   </iso:PhysicalObject>
>
>
>
>>(where iso: is the namespace prefix that gives you the rest of the full
>
>
>>ISO URI).  This is a typical RDF "typed node" abbreviation, and it works
>
>
>>the same way in OWL (as an RDF language).  This is what I meant by
>
>
>>saying I didn't see the need to use owl:Thing explicitly.
>
>
>
>>I'm assuming that http://www.iso15926.org/part2/2003-12#PhysicalObject
>
>
>>is already defined as an OWL class, since your original message spoke of
>
>
>>rdf:typing the instances with the applicable OWL classes.  That being
>
>
>>the case, if you define the instance as an instance of that OWL class,
>
>
>>the OWL semantics specify that it's also an instance of owl:Thing,
>
>
>>without you having to explicitly say so.  Thus as I see it the issue
>
>
>>isn't about whether or not you want to be rigorous in distinguishing
>
>
>>instances from classes (doing so is always a good idea), it's about
>
>
>>whether or not you want to take advantage of built-in OWL semantics to
>
>
>>simplify the syntax you write.
>
>
>
>>However, as I said above, I may be missing something, and it won't hurt
>
>
>>to write owl:Thing explicitly if you want.
>
>
>
>
>>>We have to work with IDs like PHO-387392 anyway, since we deal with more
>
>
>>>than 20,000 classes and hundreds of thousands of individuals (all the
>
>
>>>things that make up an entire oil refinery, and the components thereof,
>
>
>>>and the process streams). We had a discussion about naming, and rejected
>
>
>>>human-understandable names. What would be the human-understandable name
>
>
>>>for a Ford Focus with a wide (not yet made) selection of engines,
>
>
>>>colors, accessories, etc? And what if that selection has been made?
>
>
>
>
>>No problem.  Lots of things are identified (for given applications) by
>
>
>>non-human understandable names (very few people refer to me in
>
>
>>conversation by my drivers license number, although the Registry of
>
>
>>Motor Vehicles insists that I have one anyway).
>
>
>
>>Cheers.
>
>
>>--Frank
>
>
>
>
>>>Regards,
>
>
>>>Hans
>
>
>
>
>
>
>
> --
>
>
>
> Ivan Herman
>
> W3C Communications Team, Head of Offices
>
> C/o W3C Benelux Office at CWI, Kruislaan 413
>
> 1098SJ Amsterdam, The Netherlands
>
> tel: +31-20-5924163; mobile: +31-641044153;
>
> URL: http://www.w3.org/People/Ivan/
>
>

--

Ivan Herman
W3C Communications Team, Head of Offices
C/o W3C Benelux Office at CWI, Kruislaan 413
1098SJ Amsterdam, The Netherlands
tel: +31-20-5924163; mobile: +31-641044153;
URL: http://www.w3.org/People/Ivan/

Received on Sunday, 30 October 2005 09:43:43 UTC

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