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RE: querying reacheability using RDQL

From: Uche Ogbuji <uche.ogbuji@fourthought.com>
Date: Tue, 28 Sep 2004 10:39:54 -0600
To: "Seaborne, Andy" <andy.seaborne@hp.com>
Cc: Alessandro Di Bella <aldib@fuurou.org>, www-rdf-interest@w3.org
Message-Id: <1096369257.4009.2176.camel@borgia>

On Wed, 2004-09-08 at 04:55, Seaborne, Andy wrote:
> Query expressions in RDQL are of fixed length so, no, you can't write an
> arbitrary reachability query.
> One way it can happen is if the source provides inference and there is
> some super property which is transitive.  Then it is just a matter of
> asking (?x :p ?y).
> An example would be rdfs:subClassOf.

Note: this is easy to express in Versa[1] without any special
arrangement in the data model

traverse(tn1, all(), vtrav:transitive)

> Do you have a concrete use case for this requirement?  The RDF Data
> Access Working group is working on a query language and it is gathering
> requirements:
> http://www.w3.org/TR/rdf-dawg-uc/

One of many example use cases: my app is about to delete a node and
wants to do simple processing on each connected node.  I'd use such a
query to get a list of resources my app can then simply iterate over.

[1] http://uche.ogbuji.net/tech/rdf/versa/

Uche Ogbuji                                    Fourthought, Inc.
http://uche.ogbuji.net    http://4Suite.org    http://fourthought.com

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Received on Tuesday, 28 September 2004 16:40:28 UTC

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