W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > June 2002

Re: new semantics initiative

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Thu, 13 Jun 2002 11:17:06 +0300
To: Pat Hayes <phayes@ai.uwf.edu>, Graham Klyne <Graham.Klyne@mimesweeper.com>
CC: RDF Core <w3c-rdfcore-wg@w3.org>
Message-ID: <B92E2FB2.16A96%patrick.stickler@nokia.com>

On 2002-06-12 20:07, "ext patrick hayes" <phayes@ai.uwf.edu> wrote:

> 
>> At 09:52 AM 6/12/02 +0100, Jan Grant wrote:
>> 
>>> Agreed; I'd rather see some syntactic mechanism for darkening (or more
>>> generally, colouring*) triples that doesn't rely on URI inspection. In
>>> particular, URI inspection doesn't need to be written into the MT
>>> documents - it should just appeal to darkness (or otherwise) that's
>>> determined through a mechanism external to the document.
>> 
>> Speaking personally, me too.  But that does seem to require a syntax
>> extension, which may be difficult at this stage.
> 
> I really do NOT want to introduce a syntax extension, which
> introduces all kinds of extra complexity.

I thought the MT already provided for such a distiction.

> We have agreed that
> contexts are out of scope.

I never proposed contexts.

> What is wrong with URI inspection?

Because you *CANNOT* know for sure what namespace URI was used
to generate some term URI by inspecting the term URI. That information
is iretrievably discarded during parsing.

Get over it folks. It can't be done. Let's please move on and
consider other, actually possible mechanisms. OK?

> One can inspect opaque URIs. RDF
> engines are going to have to be able to at least match one uriref
> with another to see if they are the same, and that is all that is
> required: if a URI is in a certain (externally defined) list of
> reserved URIs, then the triple isn't asserted. That's all.

If that's what you want to do, then simply re-introduce
rdfs:aboutEachPrefix but having as its scope the graph rather
than an RDF/XML instance, and allow folks to say

<rdf:Description rdfs:aboutEachPrefix="http://abc.com/blarg/">
   <rdf:type rdf:resource="&rdfs;Unnasserted"/>
</rdf:Description>

and then let the reasoners apply such prefix inspection as
they like on the fly.

But I agree, that's silly. The execution overhead will be huge.

Rather, the graph syntax should have an explicit mechanism
that 'colors' triples as asserted or unasserted, and implementations
can then generically and efficiently separate the two.

Doing things by URI inspection will be IMO prohibitively
expensive.

Patrick

--
               
Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Thursday, 13 June 2002 04:12:57 EDT

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