Re: What are we asking of a data model?

Let see, I guess that Bob meant:
"A data model is presented, based on the extension of the concept of a DBTG owner-coupled set to permit static and dynamic sets and a new kind of set referred to as a virtual set. The notion of connection fields is introduced, and it is shown how connection fields may be used to construct derived information bearing set names, and hence permit the specification of (dynamic) sets which are not predeclared in a schema. Virtual sets are shown to reflect the functional dependencies which can exist within a file. A technique which permits the data model to be fully described diagrammatically by extended Bachman diagrams is described. A predicate calculus for manipulation of this data model is presented. Expressions written in this calculus are compared with corresponding expressions in a relational predicate calculus, DSL ALPHA. An argument for the relational completeness of the language is given."? Or perhaps: "To sum up, it is proposed that most users should interact with a relational model of the data consisting of a collection of time-varying relationships (rather than relations). Each user need not know more about any relationship than its name together with the names of its domains (role qualified whenever necessary).[see note 3] Even this information might be offered in menu style by the system (subject to security and privacy constraints ) upon request by the user." Or,...
"Bob Badour" <bbadour_at_golden.net> wrote in message news:aLOdnSsB65zwhp7dRVn-iQ_at_golden.net...
> "SPeacock" <Xpeacock_at_pacbell.net> wrote in message
> news:4001BE3B.3BFF4B97_at_pacbell.net...
> >
> > "Dawn M. Wolthuis" wrote:
> >
> > > I'm sure we cannot get unanimous agreement on this, but can we get a
> good
> > > statement of what it is we are trying to accomplish with a data model?
> > >
> > > For example, it seems that some are asking a question such as "What
> > > mathematical model for structuring data is the simplest we can find
for
> > > hosting predicates and related propositions?" (and I'm sure someone
> else
> > > can word that better, so please take a crack at it)
> > >
> > > while others are asking: "which data model is most likely to yield
> database
> > > implementations that are the most cost-effective for the development
and
> > > on-going maintenance of software applications?" (again, not a
> > > perfectly-stated question).
> > >
> > > I am looking for answers to the latter question. My interest is in
data
> > > models whose implementations yield software developer productivity
both
> with
> > > initial development of applications and on-going support.
> > >
> > > If we were able to set up a contest to collect emperical evidence from
> > > various data model implementations and how they relates to developer
> > > productivity, would that have any bearing on this discussion or would
> some
> > > database theorists consider such scientific (emperical) data
collection
> to
> > > be irrelevant to what they care about? I recognize that no
> implementation
> > > perfectly matches a mathematical model, so perhaps some are more
> interested
> > > in comparing only the models and not looking at what these models have
> to do
> > > with actual database implementations.
> > >
> > > Thanks for any insight you can give on this. --dawn
> >
> > The main purpose for a data model is to represent the relationships
> between
> > data.

>

>