RE: A summary of the proposal for resolving the issues with rdf:text --> Could you please check it one more time?

The quoted text seems to be relative to the wiki version - I haven't reviewed all that document.

Modified (3).

The SHOULDs should be MUSTs (maximum encouragement for interoperability).

The important concept seems to be data exchange between systems that understand rdf:text and those that don't.  If information originates in an OWL2 system, it is still desirable that the information, when published as RDF, is most accessible to RDF systems.  As language tags and strings are important for presentation to people, retaining the language tag is valuable.

The two points of dada exchange I can identify are "RDF graph exchange" (already mentioned) and SPARQL over entailment regimes that include rdf:text entailments.  Note that a single SPARQL query can be over multiple graphs with different entailment regimes.

SPARL provides the extension framework - rdf:text then gives the necessary resteictions.  This should come form the rdf:text document because the SPARQL spec gives a framework for experts in the extensions to populate.

Rough text - please feel free to improve the text.

"""
Systems that employ SPARQL with entailment regimes that cover D-entailment of rdf:text, MUST expose their results in the RDF forms.  This condition is met when the scoping graph contains literals in the RDF forms plain literals and xsd:string and does not mention rdf:text as a datatype.
"""
Ref: "12.6 Extending SPARQL Basic Graph Matching"
http://www.w3.org/TR/rdf-sparql-query/#sparqlBGPExtend


Comment:

This still lets rdf:text out into RDF because it may be a OWL2 system not providing the rdf:text D-entailment (OWL RL for example??) in which case ^^rdf:text literals will 

 Andy

> -----Original Message-----
> From: Boris Motik [mailto:boris.motik@comlab.ox.ac.uk]
> Sent: 21 May 2009 10:33
> To: Seaborne, Andy; 'Alan Ruttenberg'
> Cc: 'Eric Prud'hommeaux'; public-rdf-text@w3.org; 'Sandro Hawke'; 'Axel
> Polleres'
> Subject: RE: A summary of the proposal for resolving the issues with
> rdf:text --> Could you please check it one more time?
> 
> Hello,
> 
> Please understand I am not an expert on SPARQL, so I don't know all the
> details
> there; therefore, I find input from experts really valuable.
> 
> Given what Andy has said below, it seems to me that we already have a
> solution
> for the issues surrounding D-entailment regarding the rdf:text literals.
> Hence,
> we should be in good shape overall.
> 
> In that light, it seems to me that there is just one issue in the
> rdf:text
> specification that might need addressing: do we want any special
> treatment of
> rdf:text literals during graph exchange? This relates to the following
> part of
> the specification:
> 
> - In the Introduction, we have the following sentence:
> 
> "Furthermore, when exchanging RDF graphs between RDF tools, typed
> rdf:text
> literals should be replaced with plain literals, thus maximizing
> interoperability between RDF tools that support rdf:text and those that
> do not."
> 
> - In Section 4 we have the following paragraph:
> 
> "Despite the semantic equivalence between typed rdf:text literals and
> plain
> literals in datatype interpretations, the presence of typed rdf:text
> literals in
> an RDF graph might cause interoperability problems between RDF tools, as
> not all
> RDF tools will support rdf:text. Therefore, before exchanging an RDF
> graph with
> other RDF tools, an RDF tool that supports rdf:text SHOULD replace in
> the graph
> each typed rdf:text literal with the corresponding plain literal. The
> notion of
> graph exchange includes, but is not limited to, the process of
> serializing an
> RDF graph using any (normative or nonnormative) RDF syntax."
> 
> 
> The question is what to do with those. I see the following
> possibilities:
> 
> (1) Drop them. The rationale behind such a decision would be that, since
> rdf:text is a datatype just like any other, and since according to Andy
> SPARQL
> contains mechanisms for dealing with this, there is no real need to keep
> this
> text in the spec.
> 
> (2) Leave them as they are. The rationale is that RDF tools should be
> "nice" to
> each other and should take into account that not all tools might support
> rdf:text and the related D-entailments.
> 
> (3) Upgrade SHOULD to a MUST. The rationale behind such a decision would
> be that
> RDF tools should be "super-nice" to each other :-)
> 
> I have a slight preference for (1): in general, I find the Occam's razor
> principle useful in technology. If things seem to work, don't tinker
> with them.
> Nevertheless, I would find both (2) and (3) perfectly acceptable.
> 
> Regards,
> 
>  Boris
> 
> > -----Original Message-----
> > From: Seaborne, Andy [mailto:andy.seaborne@hp.com]
> > Sent: 21 May 2009 11:19
> > To: Boris Motik; 'Alan Ruttenberg'
> > Cc: 'Eric Prud'hommeaux'; public-rdf-text@w3.org; 'Sandro Hawke';
> 'Axel
> > Polleres'
> > Subject: RE: A summary of the proposal for resolving the issues with
> rdf:text
> > --> Could you please check it one more time?
> >
> >
> >
> > > -----Original Message-----
> > > From: Boris Motik [mailto:boris.motik@comlab.ox.ac.uk]
> > > Sent: 20 May 2009 14:39
> > > To: 'Alan Ruttenberg'
> > > Cc: 'Eric Prud'hommeaux'; Seaborne, Andy; public-rdf-text@w3.org;
> > > 'Sandro Hawke'; 'Axel Polleres'
> > > Subject: RE: A summary of the proposal for resolving the issues with
> > > rdf:text --> Could you please check it one more time?
> > >
> > > Hello,
> > >
> > > This is a purely SPARQL problem: SPARQL should specify precisely
> what
> > > the
> > > semantics of BGPs under the D-entailment regime is.
> > >
> > >
> > > I am just going to briefly speculate as to how this might be done. I
> > > strongly
> > > believe this should be done declaratively -- that is, without taking
> > > into
> > > account implementations. Hence, one might use the following
> definition:
> > >
> > >     Given an RDF graph G and a BBP Q, a substitution s for variables
> in
> > > Q is
> > >     an answer to G and Q iff G D-entails s(Q).
> > >
> > > Take the following example:
> > >
> > > G = { <a, b, "01"^^xsd:integer> }
> > > Q = { <a, b, ?x> }
> > >
> > > Then, the following substitutions are answers to Q over G:
> > >
> > > s1 = { ?x --> "1"^^xsd:integer }
> > > s2 = { ?x --> "01"^^xsd:integer }
> > > s3 = { ?x --> "1"^^xsd:decimal }
> > > s4 = { ?x --> "001.000"^^xsd:decimal }
> > > etc.
> >
> > The first SPARQL WG included a mechanism for other entailment regimes.
> This
> > framework allows any group to define their own entailment regime
> without
> > requiring some future SPARQL-WG exists or be running at the time.  The
> > framework has an approach for this situation.
> >
> >  Andy

Received on Thursday, 21 May 2009 20:44:19 UTC