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Re: Editorial changes in Section 2.5

From: Pat Hayes <phayes@ihmc.us>
Date: Sat, 28 Jan 2006 00:08:29 -0600
Message-Id: <p06230905c000b91b8120@[]>
To: Enrico Franconi <franconi@inf.unibz.it>
Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>

>On 27 Jan 2006, at 22:47, Pat Hayes wrote:
>>>option b)
>>>Two basic graph patterns are graph-equivalent if they are the same 
>>>up to bnode renaming.
>>I suggest we use the informal version, but include a link to the 
>>normative formal version already published. Its a good idea 
>>generally to link to other specs rather than repeat content:
>>Two basic graph patterns are 
>>graph-equivalent</a> if they are the same up to bnode renaming.
>I agree about choosing (b), but please note that the old definition 
>does *not* work for BGPs because there are variables as well to map; 
>so we can't refer to it directly (unless you say explicitly that it 
>is the same by considering variables as well).

Ah yes, of course. Damn. Let me think about that more.

>>>2) Definition of scoping set does not emphasise the simple fact 
>>>that in general it is an arbitrary subset of the RDF terms. So I 
>>>A Scoping Set B is an arbitrary subset of the RDF terms.
>>But this could be understood as saying that B is required to be 
>>arbitrary, i.e. cannot be further restricted by other specs, which 
>>would be very misleading. How about being even more explicit:
>>A scoping set B is some set of RDF terms. This is an arbitrary 
>>parameter in this definition. The contents of B should be 
>>restricted to correspond appropriately to different entailment 
>OK for me.
>>>3) Typo in the definition of scoping graphs (s/The/A/).
>>>The Scoping Graph G' for RDF graph G, is an RDF Graph that is 
>>>graph-equivalent to G
>>>A Scoping Graph G' for RDF graph G, is an RDF Graph that is 
>>>graph-equivalent to G.
>>Actually that was not a typo. I prefer the definite article, to 
>>emphasize that we are talking about a single scoping graph for all 
>I now see this, but apparently was confusing to external readers. 
>Can you find a better rephrasing?

I'll need to work with the whole text in front of me, will try 
tomorrow evening.

>>I know I lost the vote, but since we are now tinkering with this 
>>yet again, let me explain why having this clause in the definition 
>>is a mistake.
>Look, I am happy that you tell us your doubts. It is not matter of 
>voting, but to find the best technical solution. The more brains are 
>united the better it is.
>>During the telecon, I thought it was just a gratuitous complication 
>>that didn't change the effect of the definition - which would 
>>itself have been sufficient reason to reject it - but in fact it is 
>>broken, since it allows the bnodes in BGP to overlap with those in 
>Jos made your example explicit, and he showed that it works :-)

Yes, but my point was that it SHOULDNT have worked. See my reply to Jos.

>Probably you misread the definition: we say
>G simply entails (G' union S(***BGP'***))
>i.e., there is BGP' inside, not BGP.

No, I didnt misread it. Did you read that BGP', not BGP, is required 
to not share bnodes with G', and do you see that this condition is 
vacuous, since both G' and BGP' are free to choose bnodeIDs to avoid 
any clashes? And since the previous version of this condition was 
critical, doesn't that alone suggest that something is wrong?

I'll try to work up a more convincing example, but its bedtime here 
now and my battery is about to expire :-)



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Received on Saturday, 28 January 2006 06:08:08 UTC

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