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Re: Comments on informal meaning of the RDFS vocabulary

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 29 Jan 2003 16:03:08 -0500 (EST)
Message-Id: <20030129.160308.130075529.pfps@research.bell-labs.com>
To: bwm@hplb.hpl.hp.com
Cc: www-rdf-comments@w3.org

From: Brian McBride <bwm@hplb.hpl.hp.com>
Subject: Re: Comments on informal meaning of the RDFS vocabulary
Date: Wed, 29 Jan 2003 19:49:54 +0000

> At 08:42 29/01/2003 -0500, Peter F. Patel-Schneider wrote:
> 
> [...]
> 
> 
> >Well, if one really believed RDF Schema, then the model-theoretic behaviour
> >of RDF should abide by whatever is said in rdfs:comment value.  For
> >example,
> 
> The following example clarifies the question very well.  Thanks.
> 
> 
> >         ex:Cretan rdf:subClassOf ex:Person .
> >         ex:Cretan rdfs:comment "All Cretans are liars" .
> >
> >would mean that the model theoretic consequences of
> >
> >         ex:John rdf:type ex:Cretan .
> 
> The text in:
> 
>    http://www.w3.org/TR/rdf-schema/#ch_comment
> 
> is:
> 
> [[
> A triple of the form:
> 
> R rdfs:comment L
> 
> states that L is a human readable description of R.
> 
> ]]
> 
> What text suggests that there is any *model theoretic* consequences of the 
> natural language interpretation of L?

The fact that the same wording is used to describe the meaning of rdf:type,
etc.


> [...]
> 
> >So, an implementor who looks to Schema for guidance on how to build an RDF
> >system is going to get the impression that there is no difference in import
> >between the meanings given to rdf:type and rdfs:label.  The implementor may
> >decide that the only suitable way of presenting resources to users is via
> >values of their rdfs:label properties.
> 
> We seem to have switched to rdfs:label.  The text at:
> 
>    http://www.w3.org/TR/rdf-schema/#ch_label
> 
> is
> 
> [[
> rdfs:label is an instance of rdf:Property that is used to provide a 
> human-readable version of a resource's name.
> 
> A triple of the form:
> 
> R rdfs:label L
> 
> states that L is a human readable label for R.
> ]]
> 
> Right, that could be tidied up:
> 
> [[rdfs:label is an instance of rdf:Property that may be used to provide a 
> human-readable version of a resource's name.]]
> 
> Would that be better?

Probably, but rdfs:label is much less of a problem than rdfs:comment.

> 
> >The implementor may decide that RDF
> >lists have unique firsts and rests and write an RDF system accordingly.  The
> >user may believe that RDF lists must always have unique firsts and rests.
> 
> That is clearly the design centre.  What text in the schema doc is
> incorrect[?] 

The following text (emphasis added)

	5.2.2 rdf:first

	rdf:first is an instance of rdf:Property that is used to indicate
	*the* first item of a list.

	A triple of the form:

	L rdf:first O

	states that L is an instance of rdf:List and that O is *the* first
	item of the list.

	[...]

	5.2.3 rdf:rest

	rdf:rest is an instance of rdf:Property that is used to indicate
	the sublist that contains the items of a list other than the first.

	A triple of the form:

	L rdf:rest O</p>

	states that L is an instance of rdf:List, that O is an instance of
	rdf:List and O is *the* list L without L's first item.

	[...]

> Brian

peter
Received on Wednesday, 29 January 2003 16:03:26 GMT

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