Re: Start discussion

On 3/22/2010 12:49 AM, Ezzat, Ahmed wrote:
> Hi Juan,
> We have tasks for the use case. I agree that I do not see enough
> discussion on the distribution list. It was agreed on we need the use
> case completed before diving deeper in the mapping language. This
> Tuesday let us discuss what is left on the use case. Our highest
> priority is to finalize what the team will be delivering sometime in
> April - higher priority than the semantics of the language.
> I agree for using Datalog in expressing the semantics of the mapping
> language; we should discuss that in the group. If I remember correctly,
> Andy Seaborne used Datalog in expressing the semantics of some SPARQL
> language constructs in the SPARQL WG...
> Lee, Independent of which approach you use, you need to validate the
> semantics of the mew language. Advantage of Datalog, as it is based on
> logic, it is more expressive than relational algebra. Below is few pages
> about Datalog.

Thanks, though I'm less concerned about expressivity then about having a 
normative reference that implementors can follow from our specification 
in order to reliably understand and implement the RDB2RDF semantics. I 
think that Marcelo is saying in 
http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2010Mar/0059.html 
that such a standard exists, but a Web search has not been helpful to me 
in finding it - can someone please share a link?

Actually, I have similar concerns about the SQL approach, as I'm led to 
believe (I'm no expert in ANSI/ISO SQL either!) that the SQL Standard is 
a complex place and not easily referenceable by a W3C specification.

Lee


> Regards,
> Ahmed
> -----Original Message-----
> From: public-rdb2rdf-wg-request@w3.org
> [mailto:public-rdb2rdf-wg-request@w3.org] On Behalf Of Lee Feigenbaum
> Sent: Sunday, March 21, 2010 5:51 PM
> To: Juan Sequeda
> Cc: public-rdb2rdf-wg@w3.org
> Subject: Re: Start discussion
> On 3/21/2010 8:26 PM, Juan Sequeda wrote:
>  > Hi Everybody,
>  >
>  > There has been no discussion at all on the list, and that honestly
>  > worries me.
> I share this concern, which is one reason that I decided to join the
> group and try to add what I can.
>  > I know that we need to have a Use Case documents, but it is not
>  > completely clear to me what else we need to turn in and by when.
>  >
>  > One issue that I personally feel than needs to be settled is the
>  > semantics of the language. One we have this defined, it is just a matter
>  > of deciding on what is the syntax. I don't think we have made much
>  > progress on this issue. I have proposed to develop the semantics of the
>  > mapping language in datalog. I'd be up for working on this in
>  > conjunction with Marcelo Arenas and Dan Miranker.
> Ideally, I'd hope that the semantics of the language follow from the
> requirements which follow from the use cases.
> As far as datalog, I know next to nothing about it, so my questions are
> probably naive. Is there a datalog standard that we will be able to
> normatively reference if the semantics of the language are given in
> datalog?
> Also, I'm not sure if separating the syntax & semantics is definitely an
> easy thing to do. I know that there are people on the group who advocate
> that the mapping language be based on SPARQL CONSTRUCT queries combined
> with a default mapping from the relational model to the RDF model. In
> this case, I imagine it would make more sense to lean on the SPARQL
> algebra/semantics?
> Lee
>  > What else should we be having discussions on? The clock is ticking.
>  >
>  >
>  > Juan Sequeda
>  > +1-575-SEQ-UEDA
>  > www.juansequeda.com <http://www.juansequeda.com>
> <http://www.juansequeda.com>

Received on Monday, 22 March 2010 12:21:55 UTC