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

RE: Unasserted triples, Contexts and things that go bump in the night.

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Thu, 4 Apr 2002 13:32:47 -0600
Message-Id: <p05101520b8d25927b2eb@[65.217.30.94]>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: w3c-rdfcore-wg@w3.org, www-webont-wg@w3.org
>Original posting to RDF Core, this message also to Webont.
>
>As I understand it, the minimal unasserted triple proposal is that at least
>for daml:collection it would have been better if the triples with properties
>daml:first and daml:rest (and maybe those ending rdf:type daml:List ), were
>somehow special.

Special in a special way: they do not make any assertions of 
propositions in the RDF MT. Of course they can be used by DAML to 
make DAML assertions.

>There is an intended syntactic restriction on these triples i.e. that each
>cell in a daml:collection has:
>- rdf:type daml:List (and no other)
>- exactly one daml:first property (pointing to a resource)
>- exactly one daml:rest property ( pointing to daml:nil or another cell )
>- no other properties.
>
>At least some of these restrictions could be described with Daml+Oil.

True, but orthogonal to the point.

>That
>approach is not compatible with unasserted triples.

?? Why not? I fail to follow your reasoning here. The idea was not 
that dark triples are invisible to DAML, only that they make no RDF 
assertions.

>Alternatively we need another language (maybe english) to describe these
>restrictions.

I would prefer to do that, myself, since they are essentially part of 
the DAML *syntax* requirements. It is usually rather tricky to have 
an assertional language which is able to describe its own syntax, and 
I don't see any real utility for this ability (unless maybe it is 
truly general-purpose and so can be used as a kind of universal 
syntax specification, as in KIF; but that goes way beyond what would 
be possible in DAML.)

>My point being that using dark triples to construct purely syntactic
>substructures within RDF graphs then begs the question of how to describe
>the syntax of those syntactic substructures.

Well, it doesn't address that question, but then it doesn't address a 
whole lot of other questions either. It wasn't aimed at that issue. I 
don't think it would interfere with any proposals along that 
direction, however.

Pat

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Received on Thursday, 4 April 2002 14:32:47 EST

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