W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > November 2001

RE: DATATYPES: mental dump.

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Thu, 15 Nov 2001 13:54:55 -0600
Message-Id: <p0510106ab819cbc72e71@[65.212.118.147]>
To: Patrick.Stickler@nokia.com
Cc: w3c-rdfcore-wg@w3.org
>  > -----Original Message-----
>>  From: ext Pat Hayes [mailto:phayes@ai.uwf.edu]
>>  Sent: 15 November, 2001 04:36
>>  To: Stickler Patrick (NRC/Tampere)
>>  Cc: w3c-rdfcore-wg@w3.org
>>  Subject: RE: DATATYPES: mental dump.
>>
>>  > >If anyone
>>  >thinks there's a better way for a given case, please suggest it.
>>
>>  I don't think the P++ option is expressible in RDF/XML, since it
>>  requires literals to be subjects.
>
>Apologies in advance for telling you what you mean by
>your P++ proposal, but... ;-)
>
>Aren't you really saying that the node in the graph, which
>is unique, and which has a literal as its label (which is
>not necessarily unique) acts as the subject of the statement.

Er...yes, you could say that. But in the same sense, all subjects are 
nodes, even those with uriref labels. I was presuming that 
'expressible in RDF/XML' meant, using the usual conventions for 
writing RDF graphs in the XML lexicalization.

With enough ingenuity, any graph structure can be *described* in XML, 
of course.

>I.e., I've understood that my X proposal was quite
>similar in principle to your P++ proposal in that it
>defines urirefs and literals as just labels of nodes,
>and nodes are unique in the graph,

I am puzzled, since this is just true of all RDF graphs: urirefs and 
literals ARE labels of nodes, and nodes ARE unique. Right. So what 
does it mean to say that the X proposal 'defines' this to be the 
case? All of RDF assumes this to be the case, surely (??)

>and one would expect
>to merge any two nodes having the same uriref label,
>but not merge two nodes having the same literal label
>(which is why there are distinct UNodes and LNodes
>in the X model)

I confess to not really understanding the X model. It seems to be a 
proposal to describe RDF graphs in RDF, a kind of meta-RDF . I don't 
really see what the point of doing this is, or how you would get back 
to the original assertions you started with.

>Thus, in fact, P++ is expressable in RDF/XML but requires
>a means to clearly denote the node identity and the
>label.
>
>So while there may not be an "elegant" way to express
>P++ in RDF/XML, I think it is at least expressable
>according to a given idiom.

If you had said just 'expressible in XML' then yes; but RDF/XML 
already is an idiom.

Pat

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Received on Thursday, 15 November 2001 14:54:36 EST

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