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Re: reply to a POWDER Group request

From: Ivan Herman <ivan@w3.org>
Date: Tue, 14 Apr 2009 06:27:30 +0200
Message-ID: <49E410B2.1010304@w3.org>
To: Michael Schneider <schneid@fzi.de>
CC: public-owl-wg@w3.org
Hi Michael,

great... your scrutiny is wonderful to have.

As you yourself suggest, I would prefer not to send our comments on 
their semantic extension part. The issue is that what they have there, 
the style they use (it does sound a bit overcomplicated to me) is in 
line with the similar extension they have elsewhere but which is 
normative (and not OWL 2 specific). I can understand their desire to 
stick as close to that as possible in purely informative section. Ie, 
unless we reviewed the normative parts, too, (which I do not believe we 
should) we should probably keep away from that part.

I will extend the answer including your additional comments.



Michael Schneider wrote:
> Hi!
> I have checked Ivan's proposal. The points in the mail seem valid to me, but I found one bug in the revised example:
> [[
> <owl:Restriction>
>   <owl:Property rdf:resource="....#hasIRI"/>
> ]]
> Should be: "<owl:onProperty ".
> Apart from this, I have found some additional points. 
> * 1st par: "At the time of this writing, the OWL-2". Should be: "OWL 2".
> * The cited reference "[OWL2]" points to the Primer. I believe the Document Overview is the best document to generically refer to OWL 2.
> The remaining points are about the Semantic Condition (extension to RDF semantics). 
> * "wdrs:hasIRI rdfs:domain rdfs:Resource .". I think we should suggest to them to change to "owl:Thing". They claim to "extend RDF semantics", but actually make use of "owl:DatatypeProperty" and "owl:FunctionalProperty", so using "owl:Thing" instead of "rdfs:Resource" seems consequent to me.  
> * I'm unsure what to do about the use of "rdf:XMLLiteral". This datatype is AtRisk in OWL 2, although it /will/ be in OWL 2 Full in any case, since it is already in the RDF Semantics. Because they extend the RDF Semantics here, they are in the scope of the RDF-Based Semantics (actually, they also extend the RDF-Based Semantics by this semantic condition).
> The remaining points are not OWL 2 specific. The WG may decide to /not/ send something about these points. I would then send a private comment.
> * "if and only if there exists uuu^rdf:XMLLiteral". Typo, should be "^^".
> * "<sss,uuu> is in the extension of the equivalence relation which relates an xsd:string with an rdf:XMLLiteral". I don't understand this, at least not the idea behind this. sss is in the range of wdrs:hasIRI and is therefore an IRI (type: xsd:anyURI). But the text talks about "an xsd:string". It sounds to me as if this "equivalence relation" is meant to relate an XML literal with its string representation. Maybe "sss" should be replaced by "x"? Anyone having a clue?
> * "<sss,uuu> is in the extension of the equivalence relation". There's no need to talk about an extension here, since there is no property (individual!) around. Although it isn't wrong, saying "is in the equivalence relation" should be sufficient.
> Michael
>> -----Original Message-----
>> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org]
>> On Behalf Of Ivan Herman
>> Sent: Tuesday, April 07, 2009 12:43 PM
>> To: W3C OWL Working Group
>> Subject: reply to a POWDER Group request
>> A few days ago the chairs received a review request from the chair of
>> the POWDER group. The essence of the mails says:
>> [[[
>> Dear OWL and DAWG Team contacts and chairs,
>> ...
>> Our Formal Semantics document
>> (http://www.w3.org/TR/2009/WD-powder-formal-20090403/) has already
>> received substantial review and is regarded (by us!) as stable. It does,
>> however, make an informative reference to OWL 2 in section 4.6 which,
>> AFIAK, hasn't elicited any comment.
>> ]]]
>> I have looked at the section in question, and have discussed it with
>> Boris and Peter because, indeed, there are some issues. The proposed
>> answer, in the name of the WG, would be below. Should be approved by the
>> group for an answer, though.
>> Ivan
>> [[[
>> Dear Phil,
>> thanks for you note. We have indeed found some problems in section 4.6
>> of http://www.w3.org/TR/2009/WD-powder-formal-20090403/ which needs
>> updates. There are as follows.
>> - The reference should be to XSD1.1 and not XSD2:
>>      http://www.w3.org/TR/xmlschema11-2/
>> - The encoding of the condition in the example has several problems
>> compared to the latest version of OWL 2. These include
>>    - namespace changes (OWL 2 refers to xsd:pattern directly and not
>> owl:pattern; reuse rdfs:Datatype instead of datarange)
>>    - we also think that the type of restriction used is inappropriate.
>> owl:hasValue should refer to a single individual value and not to a
>> datatype/datarange. Based on the rest of the POWDER semantics, what you
>> probably have to use is owl:allValuesFrom, but this is something you
>> have to decide.
>>    - the RDF mapping of facets is based on a list of blank nodes
>> instead of the approach used in the code
>> The first example (the second has similar structure) should look
>> something like:
>> <owl:Restriction>
>>  <owl:Property rdf:resource="....#hasIRI"/>
>>  <owl:allValuesFrom>
>>    <rdfs:Datatype>
>>      <owl:onDatatype rdf:resource="..XMLSchema-datatypes#string"/>
>>      <owl:withRestrictions rdf:parseType="Collection">
>>        <rdf:Description>
>>          <xsd:pattern rdf:datatype="#string">YOURPATTERN</xsd:pattern>
>>        </rdf:Description>
>>      </owl:withRestrictions>
>>    <rdfs:Datatype>
>>  </owl:allValuesFrom>
>> </owl:Restriction>
>> We are sorry not to have spotted this issue earlier.
>> Sincerely
>> Ivan Herman
>> In the name of the OWL 2 Working Group
>> ]]]
>> --
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> mobile: +31-641044153
>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>> FOAF: http://www.ivan-herman.net/foaf.rdf
> --
> Dipl.-Inform. Michael Schneider
> Research Scientist, Dept. Information Process Engineering (IPE)
> Tel  : +49-721-9654-726
> Fax  : +49-721-9654-727
> Email: michael.schneider@fzi.de
> WWW  : http://www.fzi.de/michael.schneider
> =======================================================================
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> =======================================================================


Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Tuesday, 14 April 2009 04:29:42 UTC

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