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Re: New Proposal (6.1) for GRAPHS

From: Sandro Hawke <sandro@w3.org>
Date: Wed, 11 Apr 2012 09:24:37 -0400
To: Andy Seaborne <andy.seaborne@epimorphics.com>
Cc: public-rdf-wg@w3.org
Message-ID: <1334150677.2249.99.camel@waldron>
On Wed, 2012-04-11 at 08:40 +0100, Andy Seaborne wrote:
> On 10/04/12 23:38, Sandro Hawke wrote:
> > Crawlers wont necessarily report all the data from each source.  For
> > instance, they could quite plausibly truncate at 100MB source text.
> >
> > With 'complete-graphs' semantics, they would have to flag that fact in
> > the metadata somewhere; with 'incomplete-graph' semantics, then I expect
> > truncating crawlers wouldn't bother to flag it, since their report would
> > still be correct.
> 
> RDF is monotonic. 

You might be overstating the case, but I certainly agree that it's best
to use monotonic logics and monotonic modeling with RDF.   

I mention this only because I have gotten pushback on this from time to
time.  For instance, when I was developing the RIF-in-RDF mapping, which
lets one convey rules (and graphs) in RDF, I made sure the mapping was
monotonic.  That is, I wanted to make sure that if some of the resulting
description triples were missing, it would not look like a complete
description of something which wasn't true.   BUT several experts in RDF
in the RIF Working Group (eg Dave Reynolds, if I recall correctly)
argued that this was not a necessary feature.   (We did end up keeping
it, though.  http://www.w3.org/TR/rif-in-rdf/

>  Adding some triple can not change the meaning of 
> something else; it can only be a further restriction on the 
> possibilities described.  Can you show how adding a declaration of 
> incompleteness of the graph semantics isn't breaking monontonicity?

Sorry, I was using the term "flag" rather loosely.  I don't mean a
separate triple which acts as a flag, but just some indication in the
dataset.

Given the modeling and vocabularies used in
http://www.w3.org/2011/rdf-wg/wiki/Graphs_Design_6.1/Crawler_Example

the flagging could be done monotonically by either using a different
class...

   [ a eg:TruncatedDereferenceOperation;
    ....
   ]

or a different property:

   [ a eg:DereferenceOperation;
     ...
     eg:partialResult ...
   ]

Okay?

      -- Sandro
Received on Wednesday, 11 April 2012 13:24:46 UTC

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