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From: munck@chance.uucp (Robert Munck)
Newsgroups: comp.software-eng
Subject: Re: Information Systems is an Engineering Discipline
Message-ID: <72778@linus.UUCP>
Date: 5 Oct 89 17:12:16 GMT
References: <1142@svx.SV.DG.COM> <34399@regenmeister.uucp> <5296@eos.UUCP> <EJP.89Oct3090900@abvax.icd.ab.com> <89277.091206UH2@PSUVM.BITNET>
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Reply-To: munck@chance.UUCP (Robert Munck)
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Organization: MITRE-McLean Software Engineering Laboratory
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In article <89277.091206UH2@PSUVM.BITNET> UH2@PSUVM.BITNET (Lee Sailer) writes:
>I think DFD's are models, ...
>"Verbal descriptions" can be models too, ...
>I wanted to point out that models are reductions of the actual system, and
>by definition they omit some detail.  ...

A good working definition of "model" is "X is a _model_ of Y if X can
be used to answer certain questions about Y."  This makes clear a number
of things about the use of models, including the importance of defining
the question set that a model is intended to answer and being careful
to limit your questions to that set.  It also says that the thing itself
is a model of itself, with no sense of "reduction."
                 -- Bob <Munck@MITRE.ORG>, linus!munck.UUCP
                 -- MS Z676, MITRE Corporation, McLean, VA 22120
                 -- 703/883-6688