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

On Wed, May 20, 2009 at 09:29:00AM +0200, Boris Motik wrote:
> Hello,
> 
> I don't see the benefit of option 1, as it makes things unnecessarily complex.
> The fewer exceptions we have, the easier it will be to actually implement a
> conformant system. The dichotomy between plain und typed literals is just an
> example of an exception that just makes implementation difficult. Instead of
> introducing more special cases, I think we should unify these whenever possible.
> 
> Furthermore, I'm not sure whether sorting out things such as the ones pointed
> out below is necessary to finalize the rdf:text specification. Please note that
> rdf:text already has a well-defined lexical and value space, and this is *the
> only* thing that we need to be able to plug rdf:text into the model theory of
> RDF. That is, given RDF graphs G1 and G2 possibly containing rdf:text literals
> and/or plain literals, using the definitions from the present rdf:text
> specification one can unambiguously answer the question whether G1 D-entails G2.
> For example, if G1 is
> 
> <a, b, "abc@en"^^rdf:text>
> 
> and G2 is
> 
> <a, b, "abc"@en>
> 
> then, according to the existing RDF model theory document, G1 D-entails G2 and
> vice versa. I don't see what else is there for the rdf:text specification to do:
> I really think that the specification is complete. If SPARQL or other
> specifications want to apply rdf:text in a different way and create special
> cases, they are free to do so; however, I don't think it is in scope of the
> rdf:text specification to solve all such problems. 

(Hesitantly re-stating use case), consider the use case of the OWLIM
plugin for Sesame. If OWLIM forward chains some triples into the
Sesame repository with objects like "bob"@en, existing SPARQL queries
on the existing Sesame engine will match them as expected. RIF rules
can consume those triples and know that any rules applying to a domain
of rdf:text apply.

Constrast that with an OWLIM which emits triples with objects like
"bob@en"^^rdf:text . These triples will not match conventional queries
intended to discover e.g. all the folks named "Bob". The Sesame SPARQL
implementation can be extended, but then we are in Pat's scenario of
fixing RDF by visiting all the deployed code.

I expect that any design of rdf:text would have it reacting to plain
literals as if they had a datatype of rdf:text and the appropriate
lexical transformation. I propose that the simplest complete design is
one where the inference of rdf:text objects results in their
expression as plain literals, avoiding a dualism between
"bob@en"^^rdf:text and "bob"@en which would lose interroperability
with existing queries, graph APIs, XPaths operating on SPARQL Results,
non-OWL inferencing systems, ...


> Regards,
> 
> 	Boris
> 
> > -----Original Message-----
> > From: public-rdf-text-request@w3.org [mailto:public-rdf-text-request@w3.org]
> > On Behalf Of Eric Prud'hommeaux
> > Sent: 20 May 2009 03:18
> > To: Seaborne, Andy
> > Cc: Alan Ruttenberg; public-rdf-text@w3.org; Boris Motik; 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?
> > 
> > On Tue, May 19, 2009 at 03:57:11PM +0000, Seaborne, Andy wrote:
> > > Apologies:
> > >
> > > > On Fri, May 15, 2009 at 11:50 AM, Seaborne, Andy <andy.seaborne@hp.com>
> > wrote:
> > > >> Monday PM end before 18:00 (GMT+1)
> > > >> Thursday PM.
> > > >> Tuesday @17:00 (GMT+1) for a short call; end before 17:30.
> > >
> > > I can't make the slot.
> > >
> > > Input: please consider interoperability of data between OWL and RDF.  Option
> > 1 is better for that than option 2 as Eric points out.
> > >
> > > This is also the least change to LC and IMHO is not a substantive change (it
> > follows on from the current graph exchange intent) to add the text needed for
> > SPARQL.  Roughly: the scoping graph of an rdf-text aware D-entailment for BGP
> > matching includes the RDF forms and does not include ^^rdf:text.  (Non-aware
> > entailment regimes would merely treat as a datatype form.)
> > 
> > does anyone oppose option 1 (plain literals are considered to satisfy
> > entailments constrained to type rdf:text and entailments of type rdf:text are
> > expressed as plain literals in the RDF graph)? (i'm wondering if we can work
> > this out before we work out scheduling this phone call.)
> > 
> > 
> > > 	Andy
> > >
> > > > -----Original Message-----
> > > > From: Alan Ruttenberg [mailto:alanruttenberg@gmail.com]
> > > > Sent: 19 May 2009 16:01
> > > > To: Axel Polleres
> > > > Cc: Seaborne, Andy; public-rdf-text@w3.org; Boris Motik; Sandro Hawke;
> > > > eric@w3.orf
> > > > Subject: Re: A summary of the proposal for resolving the issues with
> > > > rdf:text --> Could you please check it one more time?
> > > >
> > > > On Mon, May 18, 2009 at 10:03 AM, Axel Polleres <axel.polleres@deri.org>
> > > > wrote:
> > > > > Alan, since you were calling for the TC, is that fixed now?
> > > > > Otherwise, I am afraid it is not possible before Friday.
> > > >
> > > > Yes, let's have whoever can make it meet at 5:30 BST = 12:30 Boston
> > > > time.
> > > > Zakim, meet on irc #rdftext for the code. I will send a code earlier if
> > > > I can.
> > > >
> > > > -Alan
> > 

-- 
-eric

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