Re: Proposal for the Direct Mapping


This is pretty scary... I was working on something exactly the same right

I've read the R2RML spec several times and I really like the way it is done
(I have some comments, but that will go later), specially the way how
everything is defined in plain english. So I was going to propose to have
the english as the normative and move the formalism to appendix. This way we
can all be happy. Anyways, you beat me to the proposal :P



Juan Sequeda

On Tue, Jul 26, 2011 at 1:41 PM, 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

Received on Tuesday, 26 July 2011 18:46:49 UTC