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Re: Proposal for the Direct Mapping

From: Ivan Herman <ivan@w3.org>
Date: Mon, 1 Aug 2011 10:36:32 +0200
Cc: rdb2RDF WG <public-rdb2rdf-wg@w3.org>
Message-Id: <095D4620-E14A-44C7-82BE-0B0E23F0F6AF@w3.org>
To: Richard Cyganiak <richard@cyganiak.de>

I would like to have a fair assessment of the work involved. There is, clearly, a disagreement on this at this moment: Juan (and maybe you) think that the rewrite is simple, ie, a matter of a few hours, mostly pushing existing texts around. Eric does not seem to think so: I have the feeling that his assessment is a much more substantial editing work compared to the existing draft. 

I would also note that, at least in


there are still a number of 'To do...' items. Obviously, any editing should finalize these for LC. These to do-s have been around for a while now, so we would also need a clear deadline on when these things are completed. 

My feeling is that the denotational and set theoretical formalisms are complete, though Eric & Alexandre should say that.

I also note that


does _not_ include the set theoretical formalism, only the old


does, although that one may be slightly out of date (I think we changed some rules on the exact format of generated URI-s). 

I am not sure whether there is another editors' draft lying around that I have missed, re the missing bit of the rules' part and the set formalism being part of the document. 

Until we have an agreement on that, we cannot really move forward. Indeed, if the proposal leads to a major rewrite of the document, then this would jeopardize our current plans for LC. I am not sure we can afford that.


On Jul 26, 2011, at 20:41 , Richard Cyganiak wrote:

> Hi all,
> The Direct Mapping document is stuck because we have a stalemate between the editors. With Last Call approaching, we need *some* way of breaking the stalemate. So here's a proposal. This is a possible new outline for the document, along with assignments of separate sections to separate editors.
>    1. Introduction
>       - What is this?
>       - How does it relate to R2RML
>       - Target audience, assumed level of knowledge
>       - RDF terms and SQL/relational terms are used as defined in 
>         documents XXX and YYY
>    2. Example (Informative)
>       - A simple two-table example
>       - Quick explanation of foreign key handling
>       - Quick explanation of tables w/o PKs
>    3. The Direct Mapping [in Plain English]
>       - “The Direct Graph of a database is the union of the Table Graphs
>          of all tables in the database.”
>       - “The Table Graph of a table is the union of the Row Graphs...”
>       - “The Row Graph of a row is ...”
>       - ...
>    A. Appendix: Formalisms (Informative)
>       - should be crisp, short, precise, with only minimum explanation
>         and examples
>       A.1 Datalog Rules
>       A.2 Denotational Semantics
>       A.3 Set-Style Direct Mapping
>    B. Acknowledgements (Informative)
>    C. References
> I see Juan and Marcelo editing A.1.
> I see Alexandre editing A.2.
> I see Eric editing 2 (which he already wrote), 3 (which *mostly* exists), and A.3.
> I don't know about 1, B, and C.
> My reasoning is that there is no objective way of picking any of the formalisms over another formalism, so the normative expression should be the lowest common denominator: plain English. By making the formalisms all informative, we free them from the burden of having to explain the direct mapping itself in a generally accessible way. The focus can be totally on presenting the formalisms in all their terseness to an audience that is familiar with datalog/denotational semantics/whatever.
> I hope this proposal aids discussion.
> Best,
> Richard

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
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Received on Monday, 1 August 2011 08:34:52 UTC

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