Re: Peter Chen and Charles Bachman

"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c794o4$24r$1_at_news.netins.net...
> I'll accept that diagrams, in themselves, are not full mathematical
> theories, but models they often are, it seems to me. What is your
> definition of "model" (as a noun)?

I'm getting tired of reading extraordinary and novel definitions of the meanings of words in this forum. Beyond a certain point, it's pointless.

There's no question at all that the E-R model is a model. I don't care what Leandro says. It was introduced as a "data model" in 1976, and I have yet to see convincing evidence that it's not. Interestingly, some of Peter Chen's more recent publications refer to E-R in the context of "information modeling." The difference between "data modeling" and "information modeling" could turn out to be trivial, or it could be of the essence in your search for what you are searching for.

I know that the difference between "data" and "information" has been central to my use of databases for 20 years.

As far as whether Bachman diagrams do or do not represent one of the origins of the "hierarchical model of data" , I have yet to reach a conclusion on that. There's no question in my mind that Bachman diagrams (which he called "Data Structure Diagrams") were used to illustrate models of data well back into the 1960s. The word "hierarchy" occurs repeatedly in Bachman's writing.

BTW, for reference, the term "data model" didn't start creeping into my vocabulary until sometime in the 1980s. And I'm hazy on how I got exposed to it. But as soon as a saw a diagram of the models, I "got the picture", so to speak. Received on Fri May 07 2004 - 19:07:05 CEST