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
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