- From: Tim Berners-Lee <timbl@w3.org>
- Date: Thu, 18 Jan 2007 16:59:23 -0500
- To: Sandro Hawke <sandro@w3.org>
- Cc: Richard Cyganiak <richard@cyganiak.de>, Michael Schneider <m_schnei@gmx.de>, chris@bizer.de, semantic-web@w3.org, semantic_web@googlegroups.com
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
>
>
>
Received on Thursday, 18 January 2007 21:59:31 UTC