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Re: semantics and RDF(S)

From: R.V.Guha <guha@guha.com>
Date: Sat, 13 Jan 2001 10:25:29 -0800
Message-ID: <3A609D99.C18AA2E1@guha.com>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: fikes@KSL.Stanford.EDU, www-rdf-logic@w3.org
One potential way to finesse at least parts of the problem
would be to isolate RDF constructs that are semantically
problematic (such as bags) and see how far we can go
with a reduced RDF.

It is interesting to note that RDFS does not use reification
or containers.

guha


"Peter F. Patel-Schneider" wrote:

> Perhaps a metaphor for the situation as Richard and I see it might be
> useful here.  We both see the glass as 90% full in the sense that there is
> a good start and there is enough to support at least non-controversial uses
> of DAML+OIL.
>
> However, I believe that we have got 90% of the way with somewhat less than
> 10% of the effort.  I believe that there are lots of serious problems
> remaining and that coming up with meaning for the rest of RDF and RDF
> Schema will be extraordinarily difficult.  Moreover, I believe that most
> uses of DAML+OIL will want to use some of the parts of RDF and RDF Schema
> that do not have a firm meaning.  Thus, although one way of measuring
> progress is that we are 90% done, another way is that we are only 10%
> done, as only 10% (or so) of the DAML+OIL ontologies will use only the
> well-specified parts of RDF and RDF Schem.
>
> As a good example of the difficulties that will be encountered, consider
> whether the following DAML+OIL ontology is consistent.
>
> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-schema-ns#"
>          xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
>          xmlns:daml="http://www.daml.org/2000/12/daml+oil#"
>          xmlns="#">
>
> <rdf:Property rdf:ID="#bar"/>
>
> <rdfs:Class rdf:ID="foo">
>   <rdfs:subClassOf>
>     <daml:Restriction daml:cardinality="1">
>       <daml:onProperty rdf:resource="#bar"/>
>     </daml:Restriction>
>   </rdfs:subClassOf>
> </rdfs:Class>
>
> <rdf:Bag rdf:ID="#bag1>
>   <rdf:li rdf:resource="#bag1">
> <rdf:Bag>
>
> <rdf:Bag rdf:ID="#bag2>
>   <rdf:li rdf:resource="#bag2">
> <rdf:Bag>
>
> <foo>
>   <bar rdf:resource="#bag1"/>
>   <bar rdf:resource="#bag2"/>
> </foo>
>
> </rdf:RDF>
>
> Peter Patel-Schneider
>
Received on Saturday, 13 January 2001 13:20:37 GMT

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