Newsgroups: comp.databases.theory Path: newssvr20.news.prodigy.com!newsmst01a.news.prodigy.com!prodigy.com!in.100proofnews.com!in.100proofnews.com!news-out.visi.com!petbe.visi.com!news.octanews.net!ash.uu.net!xyzzy!nntp From: "D Guntermann" Subject: Re: Peter Chen and Charles Bachman X-Nntp-Posting-Host: e228711.nw.nos.boeing.com Message-ID: X-Mimeole: Produced By Microsoft MimeOLE V6.00.2800.1165 X-Priority: 3 X-Msmail-Priority: Normal Lines: 55 Sender: nntp@news.boeing.com (Boeing NNTP News Access) Organization: The Boeing Company X-Newsreader: Microsoft Outlook Express 6.00.2800.1158 References: Date: Wed, 5 May 2004 17:52:33 GMT Xref: newssvr20.news.prodigy.com comp.databases.theory:26218 "Dawn M. Wolthuis" wrote in message news:c7ando$tol$1@news.netins.net... > "Leandro Guimarães Faria Corsetti Dutra" wrote > in message news:pan.2004.05.05.02.38.23.931293@dutra.fastmail.fm... > > Em Tue, 04 May 2004 17:16:28 -0500, Dawn M. Wolthuis escreveu: > > > > >> Diagrams aren't models... > > > > > > 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)? > > > > A model must include all aspects of the database, or it will > > be only a draft. Wouldn't a model that includes all aspects of the database be an implementation? Perhaps the word "all" is a little strong. > > With the number of dialogs we have that include information relevant to > databases, but "orthogonal" to relational theory, my conclusion is that by > your definition relational theory is not a model -- is that correct? I don't want to put words in his mouth, but I think he is arguing just the opposite. I'm sure many in this group have already seen the article, but the following by Chris Date gives rise to what I agree are some of the issues and distinctions that are relevent to what we call and how we use models. See "Models, models, everywhere, nor any time to think." (http://www.pgro.uk7.net/cjd3a.htm). - Dan > > > > > A diagram can hardly be expected to represent, say, all > > constraints in a database. > > > > Not to mention their maintenance tends to become > > counterproductive as the database grows in complexity and size. > > > > They are nice as drafts in the early stages of modelling and > > for presentation. > > > > > > -- > > Leandro Guimarães Faria Corsetti Dutra +55 (11) 5685 2219 > > Av Sgto Geraldo Santana, 1100 6/71 +55 (11) 5686 9607 > > 04.674-000 São Paulo, SP BRASIL > > http://br.geocities.com./lgcdutra/ > >