W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > January to March 2006

Re: Editorial changes in Section 2.5

From: Pat Hayes <phayes@ihmc.us>
Date: Mon, 30 Jan 2006 16:57:19 -0600
Message-Id: <p0623090ac0044509b590@[10.100.0.23]>
To: Enrico Franconi <franconi@inf.unibz.it>, "Seaborne, Andy" <andy.seaborne@hp.com>
Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>

>On 30 Jan 2006, at 19:01, Seaborne, Andy wrote:
>
>>Enrico Franconi wrote:
>>
>>>Why do we still have a long definition of Scoping Set, while we  
>>>probably just want to say that it is an 
>>>arbitrary subset of the RDF  Terms (as we say 
>>>after: "A scoping set B is some set of RDF 
>>>terms.")?
>>>Maybe you have an argument for it.
>>
>>I am waiting for agreement within the WG in 
>>nearby areas.  The stress on all IRIs and all 
>>literals and some blank nodes was suggested at 
>>one time and is left for now.
>
>I'm waiting for Pat's OK, then.

As you know, Id prefer to have this very general 
definition somewhere else. But if it has to be 
here, lets keep it as short and painless as 
possible. So I vote that we just say that the 
scoping set is is some set of identifiers:

>
>>>"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 regimes."
>>>==>
>>>"A scoping set B is some set of RDF terms. The 
>>>scoping set restricts  the values of variable 
>>>assignments in a solution. The scoping set may 
>>>be characterised differently by different 
>>>entailment regimes."
>>
>>Not done.  This is the text that Pat proposed and you agreed with.
>>http://lists.w3.org/Archives/Public/public-rdf-dawg/2006JanMar/0311
>
>Yes, but the proposed change is definitely much 
>more understandable, I believe.
>I'm waiting for Pat's OK, then.

I'm OK with that change.

>
>>>"""
>>>Definition: Basic Graph Pattern E-matching
>>>Let E-entails be an E-entailment regime,
>>>BGP a basic graph pattern,
>>>G an RDF graph,
>>>G' a scoping graph for G,
>>>B a scoping set, and
>>>S a pattern solution.
>>>BGP E-matches G with pattern solution S with respect to a scoping
>>>graph G' and scoping set B,
>>>if there is a basic graph pattern BGP' that is graph equivalent to BGP,
>>>such that:
>>>1/ G' and BGP' do not share any blank node labels,
>>>2/ (G' union S(BGP')) is a well-formed graph for the E-entailment,
>>>3/ G E-entails (G' union S(BGP')),
>>>4/ The range of S is equal to B.
>>>"""
>>
>>Awaiting consensus.
>
>I'm waiting for Pat's OK, then.

I still think the introduction of BGP' is a 
technical mistake: but even if it is not, it is 
still an expository and mathematical mistake, 
because there is no need for it. The definition 
was correct, shorter and clearer without it. So 
you are not going to get my OK on this, I'm 
afraid. IMO the definition of G' (scoping graph) 
should ensure that it shares no bnodes with any 
BGP in the query - so it is a scoping graph *for 
the query*, not for G - and then the definition 
above should read:

BGP E-matches G with pattern solution S with 
respect to a scoping graph G' and scoping set B 
when:

(1) (G' union S(BGP')) is a well-formed graph for the E-entailment regime,
(2) G E-entails (G' union S(BGP))
(3) The range of S is a subset of B

The condition about not sharing any blank nodes 
between G' and BGP should be part of the 
definition of 'scoping graph', not of E-matching. 
(I just noticed the need for 'subset': Enrico, 
you agree? Each answer has a distinct S.)

>>What would help me is one sentence that captures the role of BGP' in
>>the same way as we have text for the scoping graph and scoping set.
>
>After the definition of Basic Graph Pattern E-matching:
>"The introduction of the basic graph pattern 
>BGP' in the above definition makes the query 
>independent of the chosen blank node names in 
>it."

But that is meaningless, since  the query is what 
it is: how can it be independent of itself? And 
in any case, this is a definition of matching 
(or, equivalently, of what counts as a pattern 
solution S), and the bnodes in the solution are 
already independent of those in the query; so the 
use of BGP' achieves nothing.

>
>>>"These definitions allow for future extensions to SPARQL. This  
>>>document defines SPARQL for simple entailment.
>>>The scoping set B is the set of all RDF terms in G'."
>>>==>
>>>"These definitions allow for future extensions to SPARQL. This  
>>>document defines SPARQL for simple entailment, with the further  
>>>restriction that the scoping set B is the set of all RDF terms in G'."
>>
>>Not done.  I think stressing the scoping set 
>>restriction is helpful and inline with the 
>>earlier remarks that different entailment 
>>regimes restrict B is their own way.
>
>Got it, but still I find the sentence not very contextualised. So what about:
>"The scoping set B is the set of all RDF terms in G'."
>==>
>"In the case of simple entailment as defined in 
>this document, the scoping set B is the set of 
>all RDF terms in G'."

Or just ==>
"Here, the scoping set is .... "

Pat


>cheers
>--e.
>
>Attachment converted: betelguese2:smime 15.p7s (    /    ) (00230696)


-- 
---------------------------------------------------------------------
IHMC		(850)434 8903 or (650)494 3973   home
40 South Alcaniz St.	(850)202 4416   office
Pensacola			(850)202 4440   fax
FL 32502			(850)291 0667    cell
phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
Received on Monday, 30 January 2006 22:57:28 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:25 GMT