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From: scottw@advsysres.com  (Scott A. Whitmire)
Subject: Re: mathematics (algebra?) of object orientation
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References: <49c627$bgn@sparcserver.lrz-muenchen.de> <49d23s$6bk@Starbase.NeoSoft.COM> <49lvuq$bv1@mujibur.inmind.com>
Date: Sat, 2 Dec 1995 03:19:25 GMT
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Xref: glinda.oz.cs.cmu.edu comp.object:41828 comp.object.logic:596 comp.theory:14807 sci.math:127021

In <49lvuq$bv1@mujibur.inmind.com>, mfinney@inmind.com writes:
>   A class is a predicate.  This predicate includes sub-predicates that
>specify the methods associated with the class.  Each of those methods
>is described by a predicate which includes a precondition predicate and
>a postcondition predicate.  The class predicate is (potentially) more than
>just the list of method definitions.  It can include additional constraints,
>some of which can be second order and generally is quite complex.
>

You may be on to something here. A question: how do you include attributes
in your model? You only discuss the class and its methods.

Another approach is to say that a class is a set of properties (state and
behavior) which can be described algebraically, at least the external view.
Internally, you almost have to go with the "set theory" approach, since you
are dealing with collections of things. (The set theory approach was
mentioned in the material I deleted.)

This view, that a class is a set of properties, is derived from Ontology,
which is basically the study of the structure and nature of things in the
natural world - part science and part philosophy.



Scott A. Whitmire             scottw@advsysres.com
Advanced Systems Research     
25238 127th Avenue SE         tel:(206)631-7868
Kent Washington 98031         fax:(206)630-2238

Consultants in object-oriented development and software metrics.

