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Re: Blank Nodes and SPARQL

From: <jos.deroo@agfa.com>
Date: Mon, 11 Jul 2005 21:44:23 +0200
To: kendall@monkeyfist.com
Cc: Amy Alford <aloomis@glue.umd.edu>, "Seaborne, Andy" <andy.seaborne@hp.com>, Dan Connolly <connolly@w3.org>, "Eric Prud'hommeaux" <eric@w3.org>, DAWG Mailing List <public-rdf-dawg@w3.org>, public-rdf-dawg-comments@w3.org, public-rdf-dawg-request@w3.org, Ron Alford <ronwalf@umd.edu>
Message-ID: <OFA5F77734.A31C240E-ONC125703B.006A1691-C125703B.006C61F0@agfa.com>

That '!' is a forward path in n3 and :s!:p can be used to identify
a blank node
e.g. in the triple :s :p _:x that _:x can be written as :s!:p

When :p is an owl:FunctionalProperty :s!:p stands for one resource
(I make quite some use of that to work with functional terms but
then the :s is mostly a rdf List)

-- 
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/




Kendall Clark <kendall@monkeyfist.com>
Sent by: public-rdf-dawg-request@w3.org
11/07/2005 21:06
Please respond to kendall

 
        To:     Dan Connolly <connolly@w3.org>
        cc:     DAWG Mailing List <public-rdf-dawg@w3.org>, Ron Alford <ronwalf@umd.edu>, 
"Seaborne, Andy" <andy.seaborne@hp.com>, "Eric Prud'hommeaux" 
<eric@w3.org>, public-rdf-dawg-comments@w3.org, Amy Alford 
<aloomis@glue.umd.edu>, (bcc: Jos De_Roo/AMDUS/MOR/Agfa-NV/BE/BAYER)
        Subject:        Re: Blank Nodes and SPARQL



On Mon, Jul 11, 2005 at 01:46:46PM -0500, Dan Connolly wrote:

> > Care to say why you claim that it doesn't make sense?
> 
> I don't understand the proposal. I don't understand how
> to relate it to what I know about logic and query languages
> (nor our charter, nor web architecture).
> These _!:foo things look like logical constants, to me;
> i.e. like URIs. But you say they're different. I don't
> understand how, except that the scope of _!:foo is
> private to a conversation between a client and a server
> (which seems to break webarch rule #1
>  http://www.w3.org/TR/webarch/#pr-use-uris ).

There are violations of #pr-use-uris hereabouts, but I don't think this
solution is one of them. (It may respond to them, it may reflect them, but 
I
don't believe it *is* one of them...) Someone should yell at the FOAF & 
OWL
people about their violations of #pr-use-uris, which happen to make SPARQL
harder than it should be, IMO.

I'm curious why or how OWL-DL got past the relevant W3C review process 
when
it seems to clearly mandate violation of #pr-use-uris. (Well, according to
one reading of webarch.) And given that that is the state of the world and
the specs as we find them, would we be overly restricting ourselves by not
recognizing this systematic violation?

It's a bit of a crap situation we've inherited, and that stinks. Again, 
IMO.

Thanks for putting yr objections on record. I think they express a
defensible position, though I think there are other ones as well.

Kendall Clark
Received on Monday, 11 July 2005 19:45:03 GMT

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