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RE: SeRQL an RDF rule language: scoping Rules vs Query in W3C wor k

From: Butler, Mark <Mark_Butler@hplb.hpl.hp.com>
Date: Mon, 3 Nov 2003 15:41:10 -0000
Message-ID: <E864E95CB35C1C46B72FEA0626A2E80820622D@0-mail-br1.hpl.hp.com>
To: "'Dan Brickley'" <danbri@w3.org>, www-rdf-rules@w3.org

Hi Dan,

You may be aware of this already, but one thing I have noted is there is
considerable overlap between RDF and the area of semistructured data
discussed [1], [2] and [3]. I think the section titled "Query Languages" is
[1] is particularly relevant here because there is a comparison between
three query languages, one, Lorel, is similar to RDQL. The other, UNQL, is
based on a concept called structural recursion that can perform queries and
transformations in a similar way to XSLT. The third, StuQL, uses Skolem
functions, which I'm afraid I am less familiar with. 

So based on this paper, I suggest that

- yes, you are right, previous work has shown there is considerable overlap
between query and rules

- the primary distinction between rules and query is that rules use
recursive functions whereas this is not always true with queries

- there are not just overlaps between rdf-query and rdf-rules, but also
potentially with XSLT, XPath and XQuery, and of course RuleML. Unfortunately
this may not make things easier from an organizational perspective.

[1] "An Overview of Semistructured Data." Suciu. SIGACTN: SIGACT News (ACM
Special Interest Group on Automata and Computability Theory). vol. 29. 1998.
http://citeseer.nj.nec.com/160105.html

[2] "Querying Semi-Structured Data." Serge Abiteboul. ICDT. 1997. pp. 1-18.
http://citeseer.nj.nec.com/abiteboul97querying.html

[3] "Semistructured data." Peter Buneman. 1997. pp. 117--121.
http://citeseer.nj.nec.com/buneman97semistructured.html

kind regards,

Dr Mark H. Butler
Research Scientist                HP Labs Bristol
mark-h_butler@hp.com
Internet: http://www-uk.hpl.hp.com/people/marbut/

> -----Original Message-----
> From: Dan Brickley [mailto:danbri@w3.org]
> Sent: 03 November 2003 15:04
> To: sesame-devel@lists.sourceforge.net; www-rdf-rules@w3.org
> Subject: SeRQL an RDF rule language: scoping Rules vs Query 
> in W3C work
> 
> 
> 
> Hi
> 
> Within W3C, we're looking into phase 2 of the Semantic Web activity.
> 
> In terms of possible new technology areas, 'Rules' and 'Query' 
> are two topics for recommendation-track work.
> 
> So I'm looking at 
> http://sesame.aidministrator.nl/publications/users/ch05s06.html with 
> some interest. The CONSTRUCT mechanism appears to provide a bridge 
> between the world of RDF query systems and RDF-based rule systems.
> 
> 	CONSTRUCT
>     	{Artist} <rdf:type> {<art:Painter>};
>                  <art:hasPainted> {Painting}
> 	 FROM
> 	     {Artist} <rdf:type> {<art:Artist>};
> 	     <art:hasCreated> {Painting} <rdf:type>
> 	     {<art:Painting>}
> 
> 
> In this light, do folks on these lists think it is sustainable to 
> maintain that there's an interesting distinction still to be made 
> between work on RDF 'query' languages vs 'rules' languages.
> 
> Can folks here imagine a workable W3C RDF Query WG constrained not to 
> get into Rules WG territory, but to maximise compatibility with a 
> (future? parallel) Working Group on Rule languages for RDF? Or are the
> two technology areas too close?
> 
> (I invite continuation of this thread on www-rdf-rules, am 
> sending this 
> to Sesame list too initially)
> 
> thanks for your thoughts on this,
> 
> Dan
> 
> 
Received on Monday, 3 November 2003 10:42:01 UTC

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