Re: RDF Issues from MusicBrainz

At 12:42 PM 8/5/01 +0100, Brian McBride wrote:
>It does occur to me that it might be a good idea to tidy up the list from
>the flip charts and any other contributions such as this folks would like
>to make into a consolidated list.  To do that would require two actions:
>
>   o folks who have knowledge of direct user experience with RDF, to
>     summarize the top issues users had to the list - as Aaron has
>     just done for MusicBrainz

I'm not sure if this counts as "user" experience, but these are the 
RDF-related issues I would have raised in presenting our experimental workw
 ith RDF, which we hope will lead to applications in trust modelling...


Issues in use of RDF
Encoding of facts and rules


* Facts
   subj pred arg2 .
   subj rdf:type monad .
   subj pred (arg2 arg3 ...) .

It's easier to start with facts expressed using n-place predicates 
--s-expressions--;  we've thought about coding these in RDF's triple-basedn
 otation.  Some current thoughts are at:
   http://public.research.mimesweeper.com/RDF/RDFFactsAndRules.html


* Rules
   Need a “handle” to the fact -- a URI:

   Reification can do this
   » [ a rdf:Statement ;
       rdf:subject subj ;
       rdf:predicate pred ;
       rdf:object ( arg2 arg3 ... ) ]

   Similar, but not reification:
   » [ a Fact ;  functor pred ;
       args ( subj arg2 arg3 ... ) ]

 From discussions held since these notes were made, I think we may do 
better to avoid reification for this purpose, if only to avoid confusion 
over the intent.


* Variables
   Resource “stands for” a variable:
   [ a Variable ; rdfs:label “?x” ]

I think this parallels the "prince" node resolution we discussed:  the 
"variable name" is used for certain kinds of presentation, but has no 
inherent significance (noting that rdfs:label is described as being for 
presentation purposes rather than identification).


Further work
• Capturing provenance: contexts?
• e.g.
   StatedBy( http:/foo.bar.com/doc, { s1(a,b,...)  s2(c,d,...)  ... } )


I don't think any of these issues bear directly on what we are 
contemplating at the present, but suggest future issues for RDF-based 
applications and generic tools.

#g
--


At 12:42 PM 8/5/01 +0100, Brian McBride wrote:
>Hi Aaron,
>
>Thanks for this.  I'm sorry you couldn't stay for the full time.  The short
>presentations did get squeezed into the last 45 mins or so of the meeting.
>
>It does occur to me that it might be a good idea to tidy up the list from
>the flip charts and any other contributions such as this folks would like
>to make into a consolidated list.  To do that would require two actions:
>
>   o folks who have knowledge of direct user experience with RDF, to
>     summarize the top issues users had to the list - as Aaron has
>     just done for MusicBrainz
>
>   o someone to volunteer to make the summary
>
>Brian
>
>
>Aaron Swartz wrote:
> >
> > I did not get to make a presentation on MusicBrainz at the F2F,
> > however I did feel it was important that I share with you the
> > top issues that Rob Kaye, the head of the MusicBrainz project,
> > had while working with RDF:
> >
> >   - Make RDF specs easier to understand
> >
> >     The spec focuses too much on the serialization. The BNF directly
> >     in the spec is useful, but really misleading. The focus of the spec
> >     ought to be more on the graph that is created, rather than the
> >     serialization of that graph.
> >
> >   - Provide more guidelines for creating vocabularies
> >         o What should be specified as part of a vocabulary?
> >         o Provide a sample vocabulary!
> >         o Should/must a vocabulary have an RDF Schema?
> >
> >   - Provide a syntax that isn't as verbose
> >         o It should also be more intuitive. I think Sergey Melnik's
> >           approach seems reasonable:
> >           (http://www-db.stanford.edu/~melnik/rdf/syntax.html)
> >
> >     - Do you have any tips on how to write a vocabulary spec
> >       for inclusion into IETF spec? Drew Streib @ freedb wants to use
> >       MM for CD lookups and he wants to push this through the IETF.
> >       Has this been done before for an RDF vocab?
> >
> > --
> > [ "Aaron Swartz" ; <mailto:me@aaronsw.com> ; <http://www.aaronsw.com/> ]

------------------------------------------------------------
Graham Klyne                    Baltimore Technologies
Strategic Research              Content Security Group
<Graham.Klyne@Baltimore.com>    <http://www.mimesweeper.com>
                                 <http://www.baltimore.com>
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Received on Monday, 13 August 2001 10:14:37 UTC