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Re: Statements/Reified statements

From: Sergey Melnik <melnik@db.stanford.edu>
Date: Wed, 22 Nov 2000 15:31:16 -0800
Message-ID: <3A1C5744.BB6E93CC@db.stanford.edu>
To: Bill de hÓra <dehora@acm.org>
CC: RDF Interest Group <www-rdf-interest@w3.org>
Bill de hÓra wrote:
> 
> Ok, and wrt below: we can bind differing 'representations of a
> statement' to statement using (s,p,o) irregardless of the resource
> that reifies. What about where 'o' is a possibly system generated
> resource that reifies a statement: can we just ask of its (s,p,o) in
> turn until we bottom out to an o that is not denoting another
> statement?

Yes. That's the nature of reification. You'd have to drill down in a
similar way when using quad reification, right?

> Just to clarify: I understand you to say that "statement isa
> resource", not "statement hasa resource". Is that correct? So in java
> for example I could practically reify a statement object by
> downcasting it to a resource for insertion into another statement
> (isa), or, I could just ask for its reified form (hasa).

Either approach can be chosen. In Stanford API, Statement extends
Resource.

> One other thing (I essentially agree with this btw). How would one
> add a reified statement to a container (such as a jena/stanford
> Model) without asserting it? Carry tables for assertions and
> refications and indicate that a statement is present in reified form
> but "not asserted here" (nah)? It's certainly simpler than
> maintaining quads.

Actually, no special mechanism for that is necessary. In my opinion,
having a reified statement in a model that is not used as subject or
object of another statement is futile; this does not add any
information. If a reified statement is used as a resource in another
statement, it is accessible via API but is not contained in the given
model.

Sergey
Received on Wednesday, 22 November 2000 18:13:19 GMT

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