Re: Fuzzy and rough

Earl Cox (ecox@metus.com)
Thu, 3 Jun 1999 18:21:30 +0200 (MET DST)

You know, I sat through a whole flock of papers at the '98 JCIS conference
at Duke, and I've read the articles, and I still can't figure out why anyone
would turn to rough sets over fuzzy relations (an NxM Cartesian fuzzy space
in its simplest form, although generalized to an R^n fuzzy space). At the
center of a fuzzy relational (the middle of the hyperspace) we have elements
that have degrees of membership [1] with gradual membership densities toward
[0] as we move outward to any of the axes.

Rough sets look suspiciously like an attempt by probability specialists (who
know nothing about fuzzy sets) to emulate the way fuzzy sets work in data
and knowledge management. Making their crisp tools fit into a non-crisp
world.

I know I am probably opening myself up to some severe criticism here, but I
have _never_ seen a clean, easy to understand picture of a rough set and an
explanation of how they work in data mining and data mapping. I am just
completing a book for Morgan Kaufmann, "Fuzzy Tools for Data Mining and
Knowledge Discovery" and decided to leave out a chapter on rough sets
because I couldn't get anyone -- even a few professors at Duke -- to give me
clean definition of what they are and how they work.

Earl

*************************** http://www.metus.com *************************
Earl D. Cox Fuzzy Logic and Computational Intelligence
CEO/President Software, Consulting, Training
Metus Systems Data Mining and Intelligent Rule Discovery
Chapel Hill, NC C/C++ Java Visual Basic

(919) 859-1736 (vox) Exploring the Mind of Business....
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AUTHOR:
"The Fuzzy Systems Handbook" (1994)
"Fuzzy Logic for Business and Industry" (1995)
"Beyond Humanity: CyberEvolution and Future Minds"
(1996, with Greg Paul, Paleontologist/Artist)
"The Fuzzy Systems Handbook, 2nd Ed." (1998)
"Fuzzy Tools for Data Mining and Knowledge Discovery"
(due Early Summer, 1999)

metin ozbek wrote in message <375608DA.C00E4B20@emba.uvm.edu>...
>check these two::
>
>1) "rough sets, theoretical apsects of reasoning about data" by pawlak, z.,
>kluwer academic, 1991, 229 p.
>2) "incomplete information: rough set analysis", by orlowska, e., (ed.),
physica
>verlag, 1998, 613 p.
>
>good luck,
>metin
>
>Ashley Piggins wrote:
>
>> Hello,
>>
>> I'm a mathematical economist interested in learning about rough sets. I
>> am told that they differ from fuzzy sets and I'm quite interested to
>> learn more about them.
>>
>> Does anyone know a good place to start?
>>
>> All the best
>>
>> Ashley
>>
>>
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