W3C home > Mailing lists > Public > www-rdf-rules@w3.org > September 2001

Re: What is an RDF Query?

From: pat hayes <phayes@ai.uwf.edu>
Date: Tue, 11 Sep 2001 15:06:52 -0500
Message-Id: <v04210104b7c41dd76100@[]>
To: Sandro Hawke <sandro@w3.org>
Cc: www-rdf-rules@w3.org
> > <joke> The syntax of RQF could be identical to that of N-triples
> > except that an RQF document must end with a literal of the form
> > [Canadian: ", eh?"] [US: ", right?"], etc.
> > </joke>
>very funny.  :-)
> > The processing appropriate to RQF would be somewhat different from
> > that for RDF. In particular, anonNodes in RQF documents would have to
> > be treated as genuine variables which can be bound to values at run
> > time, as discussed in section 3. A unification process which binds an
> > RQF variable to an RDF uriref or anonNode would be a central part of
> > the machinery for linking RDF assertions to the RQF queries which
> > they entail.
>I don't see anything terribly wrong with having multiple formats and
>protocols (such as for assertion and query), but would you agree we
>could do it all with assertions?

Not really. I think assertions and queries (in one sense of query) 
are at opposite ends of the implication arrow, and we need to make 
clear which end we are intending something to be at.

>Instead of being able to make assertions
>      "Ralph is in his office."
>and make queries
>      "Is Ralph is in his office?"
>and maybe make weak assertions (or I dunno what-all)
>      (I suspect that) "Ralph is in his office."
>we could just use assertions for everything:
>       "Ralph is in his office."
>       "I want to know whether Ralph is in his office."

The trouble with this is that it invites the response: "So? Why 
should I care what you want?"  which would be impolite in human 
discourse, of course, but only because humans have a mutually agreed 
set of social conventions about being helpful to one another, etc. . 
Without some such conventions, nothing particular follows from your 
needing something.

>       "I suspect that Ralph is in his office."
>Of course this requires a vocabulary (ontology) for expressing wanting
>to know things (queries) and suspecting things (weak assertions) or

What we really need here is a set of agreed protocols for asking, 
asserting, querying, whatever, which are related in systematic ways 
to the contents of what are asserted, queried, etc.

>But as to existential variables: yes, if we can't get existential
>variables in the basic assertion language,

Well, RDF has them, so relax :-)


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Received on Tuesday, 11 September 2001 14:05:30 UTC

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