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Re: RDF 2.0 Wishlist - Legal RDF which I can't SPARQL

From: Ivan Mikhailov <imikhailov@openlinksw.com>
Date: Sat, 31 Jul 2010 18:34:19 +0700
To: Paul Gearon <gearon@ieee.org>
Cc: Semantic Web <semantic-web@w3.org>
Message-ID: <1280576059.29462.1676.camel@octo.iv.dev.null>
Hello Paul,

On Thu, 2010-07-29 at 10:25 -0400, Paul Gearon wrote:

> Well it's reasonably well known that it's possible to write N3 that
> can't be encoded in RDF/XML, and that doesn't seem to have caused
> great stress until now. Personally, I *much* prefer N3, so it doesn't
> bother me what RDF/XML can't do.  :-)
> 
> As for being queried in SPARQL, that's a relative concept...
> if you really did want to search for it, you could bind to a variable,
> and FILTER on its string representation. Yes, it will be slow...

I intended to write that any query processor should be able to optimize

{ ?s ?p ?o .
  FILTER (isIRI(?o) && str(?o) = """fake://`backquoted`""") }

into internal equivalent of

?s ?p <fake://`backquoted`>

but suddenly I've found that my own optimizer miss this rewriting in
some cases. Oops! I overslept this because our clients tend to write

{ ?s ?p ?o .
  FILTER (isIRI(?o) && ?o = iri("""fake://`backquoted`""")) }

that is optimized correctly.

So thank you for the reason for fix and for an extra reason for iri()
built-in in SPARQL 1.1 .

Best Regards,

Ivan Mikhailov
OpenLink Software
http://virtuoso.openlinksw.com
Received on Saturday, 31 July 2010 11:42:52 UTC

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