Re: A statement on dbdebunk.

Erwin wrote:
> One of the last posts on dbdebunk ("On conceptual modeling and database
> design") included the following :
>
> <quote>
> My material is sound because unlike all the stuff floating in the
> industry, the logical level is formal and the conceptual level was
> developed to allow 1:1 mapping to it.
>
>
>
> · Conceptual model: informal business concepts
> (enterprise-specific)
>
> · Logical model: formal representation (as much semantics as a
> system is capable of "understanding") (enterprise-specific)
>
> · Physical model: implementation in hardware/software
> (enterprise-specific)
>
> · Data model: A "formal mapping construct" to map conceptual to
> logical models (universal theory of data)
>
> </quote>
>
> Note in particular :
>
> Conceptual model === INFORMAL
> Logical model === FORMAL
> Conceptual model "ALLOWS A 1:1 MAPPING" to the logical model
>
> Now, it seems to me that "allows a 1:1 mapping" means that there is
> some kind of isomorphism between the things that are mapped in such
> way.
>
> And the fact that some kind of isomorphism between two things can be
> found, implies that any quality or property that holds/exists/is proven
> for either of the things mapped, necessarily also holds/exists for the
> other thing mapped.
>
> So if model X has the property of being formal in some sense, and model
> Y is in some way isomorphic to model X, then it necessarily follows
> that model Y is also formal in that same sense as model X is formal .
>
> So the statements quoted here, seem contradictory to me, if not
> quackery.
>
> Anyone care to correct me on this, or comment in any other way ?

Fabian has already explained it in his article "Something To Call One's Own" which seems to be in the zipped free archives in his site. http://www.dbdebunk.com/content2001.html For some of his relevant online references, see: http://www.inconcept.com/JCM/May2003/Pascal.html http://www.inconcept.com/JCM/October2003/Pascal.htm Received on Fri Aug 18 2006 - 15:58:29 CEST