Re: Review XML Data in RIF

On Wed, 20 Oct 2010 16:11:26 +0200
Christian De Sainte Marie <csma@fr.ibm.com> wrote:

> Hi Michael,
> 
> Thanx for the quisk feedback.
> 
> Michael Kifer <kifer@cs.stonybrook.edu> wrote on 19/10/2010 19:55:34:
> > 
> > I am ok with the revised "conservative" notion of entailment + the 
> > explanations
> > per the above.
> > 
> > [...]
> > 
> > I think the doc should include the revised definition (the 
> > conservative one that
> > is currently there as of today). We can add an editor's note with the 
> earlier
> > definition and state that it is unclear whether that other notion is 
> also
> > needed.
> 
> I changed the doc to say:
> Definition (Logical entailment of a RIF BLD+XML data combination). Let φ 
> and ψ be (document or non-document) formulas. We say that a RIF BLD+XML 
> data combination <φ, E, S> entails the RIF BLD+XML data combination <ψ, E, 
> S>, denoted <φ, E, S> |= <ψ, E, S>, if and only if every model of the RIF 
> BLD+XML data combination <φ, E, S> is also a model of the RIF BLD+XML data 
> combination <ψ, E, S>.  ? 
> Notice that, in the case where E and S are empty, that is, if a RIF-BLD 
> formula is combined with an empty XML data set and an empty set of XML 
> schema definitions, the interpretation of that RIF BLD formula under a RIF 
> BLD+XML data combined multi-interpretation (?, ?, ?) is still different 
> from its interpretation under the standard RIF BLD semantics as defined in 
> [RIF BLD]. 
> Example 2.4. Let expr be a well-formed XPath 2.0 expression, and let 
> φ = Forall ?x ?y ?z (?x["fn:data(expr)"->?z] :- ?x["expr"->?y]) 
> ψ = Forall ?x ?y ?z (?y["fn:data(.)"->?z] :- ?x["expr"->?y]) 
> Notice that <φ, ?, ?> |= <ψ, ?, ?>, provided that the pair (fn, 
> http://www.w3.org/2005/xpath-functions) belongs to the statically known 
> namespaces when the XPath expressions are evaluated; but φ |? ψ. This is 
> because the xs:string constants "expr", "fn:data(expr)" and "fn:data(.)" 
> are interpreted as simple string constants, if the formulas are 
> interpreted under the standard RIF BLD semantics; whereas they are 
> interpreted according to the XPath 2.0 semantics of their literals, if the 
> formulas are interpreted under the semantics of RIF+XML data combination. 
> Editor's Note: An alternative, less conservative definition for logical 
> entailment in a RIF BLD+XML data combination would be: Let φ and ψ be 
> (document or non-document) formulas. We say that φ entails ψ in a RIF 
> BLD+XML data combination if and only if every model (E, ?, S) of any RIF 
> BLD+XML data combination <φ, E, S> is also a model of the RIF BLD+XML data 
> combination <ψ, E, S>.? The use cases for the broader definition remain 
> to be examined.

Sounds good. I simplified the formulation slightly.

> 
> Also, I added the following statement in the previous section, on the 
> combined interpretation of RIF BLD non-doc formulas.
> Notice that the semantics of XPath 2.0 expressions may entail that two 
> different expressions, evaluated with respect to two different [context 
> nodes]XP, must select the same sequence; and, therefore, that the two 
> different pairs of [context node]XP and XPath expression must have the 
> same RIFValue. This implies, per clause 1, in the definition of a RIF 
> BLD+XML data combined interpretation, above, that the RIF BLD+XML data 
> combined interpretation of frames with different objects and attributes 
> may be constrained by the semantics of XPath 2.0 expression, even in the 
> absence of XML data in the combination (see, for instance, example 2.4, 
> below). 
> 
> And I added in the introduction the following statement:
> The semantics of RIF combinations with XML data imports the semantics of 
> the XPath2.0 expressions that are used to relate RIF formulas to XML data: 
> as a consequence, the interpretation of RIF formulas in a combination with 
> XML data is more restrictive than their interpretation outside of a 
> combination, even if the XML data in the combination is empty. Notice, 
> however, that, in practice, there can never be an ambiguity regarding 
> under what semantics a RIF document must be interpreted: a RIF document is 
> interpreted under the combined semantics specified in the document if and 
> only if it imports XML data or XML schemas explicitly. 

I find that these two paragraphs are hard to understand. Both because of the
sentence structure and also because at that time the reader has no idea what
you are talking about. I think it is enough to just say that XML combined
semantics constrains certain properties and gives them special semantics. As a
result, XML+RIF where the XML document is empty is not the same as RIF alone.
Something like that.

michael

> 
> Does that work with you?
> 
> If yes, and neither Gary nor Adrian has objections, we can publish as WD.
> 
> Please, let me know.
> 
> Cheers,
> 
> Christian
> 
> IBM
> 9 rue de Verdun
> 94253 - Gentilly cedex - FRANCE
> Tel./Fax: +33 1 49 08 29 81
> 
> Sauf indication contraire ci-dessus:/ Unless stated otherwise above:
> Compagnie IBM France
> Siege Social : 17 avenue de l'Europe, 92275 Bois-Colombes Cedex
> RCS Nanterre 552 118 465
> Forme Sociale : S.A.S.
> Capital Social : 612.509.964 €
> SIREN/SIRET : 552 118 465 03644
> 
>

Received on Wednesday, 20 October 2010 17:35:53 UTC