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RE: In RDF what is the best practice to represent data provenance (source)?

From: Hans Teijgeler <hans.teijgeler@quicknet.nl>
Date: Thu, 18 Jan 2007 23:37:04 +0100
To: "'Tim Berners-Lee'" <timbl@w3.org>
Cc: "'Sandro Hawke'" <sandro@w3.org>, "'Richard Cyganiak'" <richard@cyganiak.de>, "'Michael Schneider'" <m_schnei@gmx.de>, <chris@bizer.de>, <semantic-web@w3.org>, <semantic_web@googlegroups.com>
Message-ID: <001301c73b51$314406c0$6c7ba8c0@hans>

Tim,

To me reification isn't a good idea indeed. But your solution only solves a
part of the problem.

Relationships between a subject and an object often are required to be a
subject or object themselves. I can observe, approve, ignore, deny,
ridiculize, and talk about, cause, etc a relationship. And I guess that a
relationship can cause other relationships.

What is meta data for one person is semantics for another, depending on
their roles. It should not be modelled differently, because that hampers
information integration. That is also what we dearly miss in OWL. But the
logicians will tell me that owl:ObjectProperty can never be made a
subClassOf owl:Class. We will plod on.

I'll stop pounding on this anvil :-)

Regards,
Hans

____________________
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Hans Teijgeler
ISO 15926 specialist
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+31-72-509 2005
www.InfowebML.ws 
hans.teijgeler@quicknet.nl

-----Original Message-----
From: semantic-web-request@w3.org [mailto:semantic-web-request@w3.org] On
Behalf Of Tim Berners-Lee
Sent: Thursday, January 18, 2007 22:59
To: Sandro Hawke
Cc: Richard Cyganiak; Michael Schneider; chris@bizer.de;
semantic-web@w3.org; semantic_web@googlegroups.com
Subject: Re: In RDF what is the best practice to represent data provenance
(source)?


The RDF spec's version of reification is not just incomplete but broken, as
it does not quote the identifiers used, it uses them.  There is an
outstanding RDF issue about it.

cwm does a reification which is not broken,  using a similar but different
ontology.

I think reification should be dropped from a future RDF spec.

I think n3's literal graphs like   <doc1> :says { alan :mother :joan 
}.   should be added as an extension.

In RDF/XML a parsetype="quote" option would do it.

Calling them "names graphs" as caught on but they are really graph literals,
as they don't have to have a URI.
To force them to have a URI would be like forcing strings, numbers, or lists
to haver URIs.
 
Tim

/me wonders what semantic-web@googlegroups.com is and what its relationship
is with antic-web@w3.org



Sandro Hawke wrote:
>> Enter named graphs.
>>
>>      :michael_graph {
>>          :reification :is_great_for :provenance_tracking .
>>      }
>>     
> ...
>   
>> And accommodating the contributions of Bob, Charlie and Dora is  
>> straightforward.
>>
>> See why reification does not have many friends?
>>
>> Surprisingly, some people choose to use reification nonetheless. Why  
>> is this so? Is it just because its unfinished empty concrete shell  
>> was left in the RDF spec? I never found a real reason, neither  
>> technical nor modelling.
>>     
>
> I see named graphs, as you present them, as a concept without an RDF
> syntax.  Reification in general is a way to give named graphs an RDF
> syntax.  Reification as defined in the current W3C specs is an
> incomplete approach giving named graphs an RDF syntax.  It handles only
> individual statements, not whole graphs, and it doesn't handle bnodes.
>
> You could argue that named graphs should not have an RDF syntax.  I
> would argue that everything should have an RDF syntax when it becomes
> useful to somebody to give it one.
>
> Of course you probably want syntactic sugar (eg curly braces), since
> working with reified graphs is so verbose, but there are lots of things
> in RDF you want syntactic sugar for.
>
>       -- Sandro
>
>
>   


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Received on Thursday, 18 January 2007 22:37:31 UTC

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