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

Re: RDF changes

From: Frank Manola <fmanola@mitre.org>
Date: Wed, 25 Apr 2001 11:43:15 -0400
Message-ID: <3AE6F093.64F5634C@mitre.org>
CC: w3c-rdfcore-wg@w3.org
This is interesting.  However, when I wrote:

> how much do existing implementations use reification, and
> exactly how do they use it?

I meant to refer to implementations that *use* RDF reification, rather
than implementations that *implement* RDF reification.  In other words,
how do people who use RDF for creating metadata for Web pages, site
descriptions, etc. actually use reification (as opposed to how to RDF
tools handle reification).  

NB:  A particular issue that I'm interested in here is exactly how it is
intended that reification be used to make a comment about some RDF
statement that is located elsewhere (at someone else's site).  For
instance, Web site foo contains (using the "standard example") "Ora
Lassila is the creator of http://www.w3.org/Home/Lassila", and Web site
bar wants to say "that statement was made by Ralph Swick".  I can use
RDF reification as defined to reify the original statement at Web site
bar, but I've lost all the context in which the original statement was
made.  I can certainly duplicate that context (like that the statement
was made at site foo) by adding additional information at site bar.  I'd
certainly want to do that if, e.g., I wanted to point out conflicting
statements that Ralph may have made at different times or locations. 
But the amount of context I might have to duplicate at the site where I
was making the statement could get arbitrarily large.  What I'd like to
do is just point to the original statement where it "lives" (that seems
like the "Web" way to do things, after all).  Some of these approaches
that involve imagining that every triple has an additional "column"
containing an identifier seem to effectively be steps in this
direction.  

--Frank

jos.deroo.jd@belgium.agfa.com wrote:
> 
> Jena and SiRPAC seem to be glad with
> 
> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>          xmlns:rdfc="http://www.w3.org/2001/rdf-core#"
>          xmlns="file:/daml/reification/n3.n3#">
> 
>     <rdf:Description>
>         <rdfc:is rdf:parseType="Quote">
>             <rdf:Description rdf:about="#subject">
>                 <predicate1 rdf:resource="#object1"/>
>             </rdf:Description>
>         </rdfc:is>
>         <predicate2 rdf:resource="#object2"/>
>     </rdf:Description>
>     <rdf:Description>
>         <rdfc:is rdf:parseType="Quote">
>             <rdf:Description rdf:about="#subject">
>                 <predicate3 rdf:resource="#object3"/>
>             </rdf:Description>
>         </rdfc:is>
>         <predicate2 rdf:resource="#object2"/>
>     </rdf:Description>
>     <rdf:Description rdf:about="#subject">
>         <predicate1 rdf:resource="#object1"/>
>     </rdf:Description>
> </rdf:RDF>
> 
> and an rdf:parseType="Quote" aware processor could build
> the appropriate contexts. Isn't that nice?
> 

-- 
Frank Manola                   The MITRE Corporation
202 Burlington Road, MS A345   Bedford, MA 01730-1420
mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-8752
Received on Wednesday, 25 April 2001 12:22:17 EDT

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