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Re: Use Case: Searching for educational learning materials

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Tue, 22 Jun 2004 12:07:02 +0100
To: Bijan Parsia <bparsia@isr.umd.edu>
Cc: kendall@monkeyfist.com, RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-Id: <20040622120702.56cc32a2@hoth.ilrt.bris.ac.uk>

On Sat, 19 Jun 2004 10:01:43 -0400, Bijan Parsia <bparsia@isr.umd.edu> wrote:

> On Jun 19, 2004, at 9:04 AM, Kendall Clark wrote:
> > On Sat, Jun 19, 2004 at 11:28:38AM +0100, Steve Harris wrote:
> >
> >>> SELECT ?x
> >>> FROM <graph>
> >>> WHERE
> >>>       (foo, rdfs:label, ?x) and
> >>>       (?x, xml:lang, "jp")
> >>>
> >>> That last bit isn't really in the graph (?), but I can't think of a
> >>> syntax for filter on literals.
> >>
> >> You could use the N3 syntax, seperating the literal from the datatype 
> >> and
> >> language with ^^ and @, eg.
> >>
> >> 	(foo, rdfs:label, ?x@jp)
> >
> > Hmm, that's an idea.
> I ran this by our FLA guy as one option from the start. This is 
> certainly how I would do it in SWI Prolog, at least for the common 
> case.

(FLA guy?)

I think this a bad idea since it requires looking inside a RDF concept
which as far as I am aware, is not usually indexed by the common
RDF/OWL systems in that manner, although this does not preclude it.
Adding this requirement to a DAWG QL I think would make it less
likely that this part would be implemented.

> The other possibility was having a filter predicate for AND clauses 
> (e.g., langEq). The latter was prefered.

This is what I would prefer, selecting the language aspect of an RDF literal
after SELECTion.  This is what SeRQL does if I recall correctly, there
is a language() predicate for the constraint section - so it is already
implementable, and implemented.  If some system did index on RDF
literal language it clearly could use this to advantage here.

> [snip]
> > I think Yoshio mentioned something back in the early days of the WG
> > about being sensitive to i18n issues, which this feature request
> > does. (If anyone needs to hear a use case, I can provide one related
> > to task computing in multilingual environments.)
> Or portals, or even ontology browsers. Anything that makes significant 
> use of rdfs:label and wants to internationalize.

I've built a few of those and it would haven been easy to look at the RDF literals
returned and try to select those with an appropriate language (this is not a
straight compare, but can  involve matches such as 'fr' with 'fr-ca')

Received on Tuesday, 22 June 2004 07:55:04 UTC

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