Re: Reverse Mapping RDF2RDF

[ snip ]
> > The relation between RDB, RDF, SPARQL and SQL should be formalized and
> > should not rely only on examples. It's called semantics preservation
> > -- a well-known problem in the compilation field -- and IMO it should
> > be in a normative section.
> > 
> > Eirc and I are totally confident that in the case of the direct
> > mapping, we can map any SPARQL query to its equivalent SQL query.
> 
> Where is the proof?

heh :-)

I think we first need to have a definitive version of RDB + Direct Mapping.

The first step is to be sure that this process is complete. For RDB,
this is done by definition, through its abstract model. The proof that
the direct mapping can react on *any* RDB instance is done
automagically -- well, not so magic :-) -- by Scala and its
type-checking.

We are still working on sparql2sql but you can already play with what
we have [1] (usable but not complete). The "confidence" I was talking
about comes from the fact I've done that kind of job (formal proof
with compilers) in the past. Actually, the chosen formalism reflects
this concern.

But again, this is out-of-scope. I nevertheless support Ivan's idea of
a WG note on this subject, but only *after* the direct mapping will be
out there, and *complete*.

Alexandre.

[1] http://dvcs.w3.org/hg/FeDeRate/

> 
> > 
> >> I scare-quote equivalence because SPARQL returns RDF terms and SQL, unless you significantly change the wire protocol, returns strings which can be parsed to RDF terms. 
> > 
> > I don't understand, a SQL result is a SQL table, not a bunch of
> > strings to be parsed. It's perfectly defined (the same way than for
> > the relation algebra).
> > 
> > Alexandre.
> > 
> >> 
> >>> That is all...
> >>> 
> >>> Ivan
> >>> 
> >>> On Nov 19, 2010, at 20:20 , Juan Sequeda wrote:
> >>> 
> >>>> Hi Ivan,
> >>>> 
> >>>> Per the agenda, it states:
> >>>> 
> >>>> 4. Reverse Mapping
> >>>> Question from Ivan re RDF2RDB (it's not in our charter, but maybe some WG
> >>>> members plan to address this?)
> >>>> 
> >>>> I'm curious about RDF2RDB. Could you expand on this. What are the use cases? Requirements?
> >>>> 
> >>>> Thanks
> >>>> 
> >>>> Juan Sequeda
> >>>> +1-575-SEQ-UEDA
> >>>> www.juansequeda.com
> >>> 
> >>> 
> >>> ----
> >>> Ivan Herman, W3C Semantic Web Activity Lead
> >>> Home: http://www.w3.org/People/Ivan/
> >>> mobile: +31-641044153
> >>> PGP Key: http://www.ivan-herman.net/pgpkey.html
> >>> FOAF: http://www.ivan-herman.net/foaf.rdf
> >>> 
> >>> 
> >>> 
> >>> 
> >>> 
> >> 
> >> 
> >> 
> > 
> > 
> > 
> > 
>

Received on Sunday, 21 November 2010 15:31:44 UTC