Re: Clean Object Class Design -- What is it?

"Steve Wart" <swart_at_deadspam.com> wrote in message news:<bb177.21697$zb.385594_at_news1.rdc1.bc.home.com>...
> "Bob Badour" <bbadour_at_golden.net> wrote in message
 

> > >Minsky criticizes predicate calculus as being insufficiently expressive
 for
> > >knowledge representation (see
> > >ftp://publications.ai.mit.edu/ai-publications/0-499/AIM-306.ps).
> >
> > I had no joy with the link above.
>
> Sorry for not warning you. The file is rather large (~8Mb) and has some
> postscript errors. I ran it through ps2pdf and it was fine.

Evidently they just scanned the old typewritten memo and postscripted it. Gah! Well I just OCR'd a published version and html'd it. So now it has OCR errors and some MSWORD "Save as HTML errors, too—but at least it is readable. It's at

www.media.mit.edu/people/minsky/papers/Frames/frames.html

>You likely will find no joy in the content either, as it is not a
rigorous mathematical paper. If you are looking for a formal model of frame systems perhaps someone else can provide a link.

Well, that is a priceless remark—seeing as many ideas in theat paper have never been formalized at all, e.g., the basic idea of 'frame-systems' (renamed 'frame-arrays" in Society of Mind). As a mathematician, I like to say that "Mathematics should be on tap, not on top"—because any particular formalization is likely to miss other important points. So most people think of frames as nothing more than property-lists, and miss the idea of introducing inheritance by re-assigning the values of default-assignments. Also, I think this may be the first paper that complains that conventional logical formalisms are too "monotonic."

> > >> Unfortunately, they made some huge fundamental mistakes in their implementation of inheritance. Inheritance applies to domains and not to relations.

The above "framework" paper also contains Scott Fahlman's original ideas about inheritance and his early discussions about the problems of deciding when (for example) an object should remember the history of its inherited properties, etc.

==

Umm, on second thought, I take most of that back. Steve Wart is right: if I hadn't been so imprecise, I might have forseen other good ideas about both OO and database-backed programming. So one always should try to think both formally and informally—and not let either approach get out of control. Received on Tue Jul 24 2001 - 03:42:31 CEST