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Re: Innovation, community and queries

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Thu, 23 May 2002 09:44:20 -0400
To: "ext Thomas B. Passin" <tpassin@comcast.net>, RDF Interest <www-rdf-interest@w3.org>
Message-ID: <B9126A74.153E4%patrick.stickler@nokia.com>
On 2002-05-23 9:03, "ext Thomas B. Passin" <tpassin@comcast.net> wrote:


> I think that it will become increasingly important to be able to deal with
> patterns of statements rather than single statements or single types of
> statements.  Think of 5-way joins in a relational database, for example.  Or
> a simple case would be to retrieve statements where there is a specific
> predicate and the object is also the subject of a statement whose predicate
> is a label and whose value is specified.
> 
> I think of stereotyped structures of statements like these as idioms.  There
> will be a great many idioms, and applications may well be specialized for
> specific ones.  A reified statement could be considered a kind of simple
> idiom.
> 
> A query language will be needed that can effectively work with idioms.
> Simple idioms, with little depth, can be handled already by some query
> langaguages (I think, but haven't tried any of them), but I think more
> support for stereotyped structures will be necessary.

I agree, and if those idioms are expressed in RDF, then why not
also the QL? 

Property values may be recursively defined by anonymous node, e.g.

Target must have a dc:creator which has a first name of "John",
a last name of "Doe" and have an age that is greater than 50
and a spouse who's first name is "Jane":

<regs:Query>
   <dc:creator>
      <rdf:Description>
         <person:firstName>John</person:firstName>
         <person:lastName>Doe</person:lastName>
         <person:age>
            <regs:QValue>
               <regs:gt>50</regs:gt>
            </regs:QValue>
         </person:age>
         <person:spouse>
            <rdf:Description>
               <person:firstName>Jane</person:firstName>
            </rdf:Description>
         </person:spouse>
      </rdf:Description>
   </dc:creator> 
</regs:Query>

Such a QL could support idioms of arbitrary depth, where
the query is simply a template to match against the RDF graph.

And folks who already know RDF can easily learn and use the
ontology to express such queries without having to learn
yet-another-language -- not to mention the benefits of being
able to use RDF and XML tools to express/view their queries.

Cheers,

Patrick

--
               
Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Thursday, 23 May 2002 09:40:40 GMT

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