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Re: Editorial thread for BGP matching

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Thu, 26 Jan 2006 10:13:20 +0000
Message-ID: <43D8A0C0.3020701@hp.com>
To: Pat Hayes <phayes@ihmc.us>
CC: RDF Data Access Working Group <public-rdf-dawg@w3.org>



Pat Hayes wrote:
>> Patrick J. Hayes wrote:
>>> Reading through, some miscellaneous comments/questions/suggestions(?).
>>> ------
>>> 2.1.4
>>> "Triple Patterns are grouped together with {}(braces)."
>>> Possibly mention here that these groupings determine scope of bnode 
>>> identifiers(?) <<Do they, in fact? That is, should we read
>>> {{_:a :p :q .}
>>> {_:a :r :b .}}
>>> as having two bnodes in it, or one? Im presuming two, as otherwise 
>>> what are the {} boundaries for? >>
>> It's two BGPs.
> 
> So, just to check I really have got this right, in this example there 
> would be two different bnodes, one in each BGP, even though those 
> BGPs use the same bnodeID. Right?

Yes - that's my understanding of the design.  It comes from the fact that 
entailment in BGP matching makes no reference to anything going on in a query.

	Andy

> 
> ...
> 
>>> Triple pattern: Why not allow bnodes in property position as well, 
>>> with the same disclaimers about not matching any current RDF graph? 
>>> There isn't any good semantic reason to forbid that case either. 
>>> (If this would require a WG decision, forget it :-)
>> The syntax allows it.  Defn fixed.
>>
>> Definition: Triple Pattern
>> A triple pattern is member of the set:
>>     (RDF-T union V) x (I union RDF-B union V) x (RDF-T union V)
>>
>>
>> (Could even add literals for complete symmetry. Not done as literals 
>> in the predicate would be rather confusing for no value.)
> 
> Agreed.
> 
> Pat
> 
Received on Thursday, 26 January 2006 10:13:30 GMT

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