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

Hello Boris,

In what forum do you suggest this be addressed?

-Alan

On Wed, May 20, 2009 at 7:38 AM, Boris Motik
<boris.motik@comlab.ox.ac.uk> wrote:
> Hello,
>
> I fully appreciate use case and I agree with your observation: this is something
> that has to be addressed. I don't think, however, that solving this problem is
> in the domain of rdf:text. The rdf:text specification merely defines yet another
> datatype by specifying it in exactly the same way as this is done in XML Schema.
> This datatype is just like any other XML Schema datatype; hence, the job from
> rdf:text's point of view is done.
>
> Furthermore, the addition of rdf:text to the mix of the supported datatypes adds
> no new conceptual problems to SPARQL: the situation with rdf:text is no
> different than with, say, xsd:integer (there are other examples as well). For
> example, assume that you have an RDF graph
>
> G = { <a, b, "1"^xsd:integer> }
>
> but you ask the query
>
> Q = { <a, b, "1.0"^^xsd:decimal> }.
>
> Clearly, G D-entails Q, so Q should be answered as TRUE in G. It is not the
> business of XML Schema to specify how this is to be achieved: XML Schema merely
> specifies what the correct answer to the above question is. It is a SPARQL
> implementation such as OWLIM that should think of how to support such a
> definition.
>
> I don't know whether a solution to the above problem (with xsd:integer and
> xsd:decimal) exists. If not, I agree that one should be developed; however, we
> would not go to the XML Schema WG and ask them to specify how should SPARQL
> handle this case, would we?
>
> The problem with rdf:text is *precisely* the same as the one that I outlined
> above. At an abstract level, it can be stated as "Several syntactic forms of
> literals get mapped to the semantically identical data values". AS demonstrated
> above, this problem exists without rdf:text, so I don't see how rdf:text brings
> anything new into the whole picture. Thus, you can apply to the rdf:text case
> exactly the same solution that you would apply to xsd:integer and xsd:decimal.
> If such a solution doesn't exist yet, then the SPARQL WG should address these
> issues, and it should do so in general for all datatypes (xsd:integer,
> xsd:decimal, and so on), not just for rdf:text.
>
> To summarize, I think that the work from the point of view of the rdf:text WG is
> *done* and that we should not do anything else in this forum.
>
> Regards,
>
>        Boris
>
>> -----Original Message-----
>> From: Eric Prud'hommeaux [mailto:eric@w3.org]
>> Sent: 20 May 2009 13:18
>> To: Boris Motik
>> Cc: 'Seaborne, Andy'; 'Alan Ruttenberg'; 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?
>>
>> 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
>>
>> office: +1.617.258.5741 32-G528, MIT, Cambridge, MA 02144 USA
>> mobile: +1.617.599.3509
>>
>> (eric@w3.org)
>> Feel free to forward this message to any list for any purpose other than
>> email address distribution.
>
>

Received on Wednesday, 20 May 2009 12:05:46 UTC