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Re: New Proposal (6.1) for GRAPHS

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Wed, 11 Apr 2012 14:55:09 +0100
Message-ID: <4F858D3D.20900@epimorphics.com>
To: Sandro Hawke <sandro@w3.org>
CC: public-rdf-wg@w3.org


On 11/04/12 14:24, Sandro Hawke wrote:
> 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?

The critical issue is what happens on the default case of no information.

	Andy
	
>
>
Received on Wednesday, 11 April 2012 13:55:46 UTC

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