Re: NN & Fuzzy Expert System (was: Re: A simple question)

Anthony Cowden (cowden@sonalysts.com)
Sun, 21 Jun 1998 15:54:50 +0200 (MET DST)

Thierry M. Marbach wrote:
>
> You got me confused here. Let me state my thoughts.
>
> Generally speaking (and excluding hybrid models), a Neural Net models how a
> process works (internally), from historical information. A Fuzzy Expert
> System models how an expert controls the system (externally); the
> information is generally human experience, although it is sometimes
> completed by historical data in order to fine tune the parameters of the
> model.
>
> So the question of performance really depends on your goals. A NN lacks any
> explanatory power, and relies on the quality and diversity of the
> historical data. A Fuzzy Expert System depends on how complete the
> knowledge of the operator is, and how well we extract that knowledge.
>
> It seems that very complicated systems are better modeled through expertise
> because the training of the NN can become both intensive and difficult, and
> the data requirements may be hard to meet. But I don't see one technique to
> be more general than the other. Even in cases of pure decision making (vs.
> control), you could collect data about the outcome of a decision and train
> a NN on it. Problem is, you probably would not be able to collect enough
> information, if any.
>
> Am I missing something, or misinterpreting what you wrote?
>
> Thierry
>
> BTW, I like Fuzzy Expert Systems better as a general rule because it is
> transparent...

You CAN have the best of both worlds with fuzzy knowledge discovery and
data mining, which creates a fuzzy system from data. Read Earl Cox's
2nd book (FL for Business and Industry).

>
> WSiler <wsiler@aol.com> wrote in article
> <1998053016062700.MAA29267@ladder03.news.aol.com>...
> > >>2. what fuzzy logic controlers can do that a Neural Net can't?"
> > >>
> >
> > >>Assuming a sufficiently broad selection of each, theoretically
> > >>nothing.
> > >
> > If the question is restricted to relatively simple fuzzy controllers,
> > the above reply may be correct. But if we enlarge the question to include
> fuzzy
> > expert systems generally, of which fuzzy controllers are a subset, then
> what
> > the fuzzy expert system can do is to model the thinking processes of an
> expert
> > in some field; neural nets, being more-or-less model-free, can't do this.
> The
> > neural net MIGHT be able to achieve about the same outputs for the same
> inputs
> > as a simple fuzzy expert system, but this is not at all the same thing as
> > modelling the expert's thinking process. In short, a NN is a hand-tuned
> tool
> > for function approximation; a fuzzy expert system is a general AI
> technique.
> >
> > William Siler
>

-- 
*********************************************************************
Anthony Cowden, Manager, Fuzzy Systems Solutions 
Sonalysts, Inc.
Fuzzy Systems Solutions: http://www.sonalysts.com/fuzzy.htm
Fuzzy Query (TM): http://www.sonalysts.com/fldq.html

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