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From: csa18@seq1.keele.ac.uk (R.J. Husmo)
Newsgroups: comp.ai.neural-nets
Subject: Re: Neural nets applied to Expert Systems?
Keywords: ptrs to lit
Message-ID: <784@keele.keele.ac.uk>
Date: 9 Jan 91 13:25:05 GMT
References: <15385@arisia.Xerox.COM> <2670@bimacs.BITNET>
Reply-To: csa18@seq1.kl.ac.uk (R.J. Husmo)
Organization: /usr/local/lib/news/organization
Lines: 61

>In article <15385@arisia.Xerox.COM> schneide@arisia.Xerox.COM (Kris A. Schneider) writes:
>>Hi folks,
>>
>>I'm in need of finding any literature or reference materials that deal with neural networks used by an expert system.  Any help?  T
>>
>>-Kris
>>schneide@arisia.xerox.com
There are very few papers on the subject of artificial neural networks (ANN)
and experts systems. My Master's dissertation concerned the relationship
between knowledge and ANNs. I didn't find any papers which were particularly
useful.

I had to invent methods for interfacing between ESs and ANNs. In short,
there is no easy way of extracting rules from a medium/large ANN.

For smaller, binary and layered, networks there are several methods, the 
easiest of which is described below:

Present all possible input combinations to the network (from 000000000, say,
to 111111111).
For each output node, record all input combinations which turn this node
ON.
Reduce these lists.

The result should be a list of input values which turn on an output node,
(i.e. disjunctive normal form)
eg:
  Oa is on IF Ia and not Ib OR
	      Ia and Ic and Id OR
	      Id.
(Oa = output node a, Ix Input node x)
There are several interesting issues here. What criteria is used to decide
whether a node is on or off?
What is the easiest way of reducing the humonguous lists produced by the
method described above?
What do we do if we have more than 12 input nodes (2^12 input combinations
is enough...)?
How do we handle fuzziness?
etc, etc...

These are, of course, only some issues revealed by my research. I may
write a paper about the findings one rainy day.

In article <2670@bimacs.BITNET> guedalia@bimacs.UUCP (David Guedalia) writes:
>   Hi, I am sorry I do not know of any refrences. But from what I
>understand of Expert Systems and Neural Nets they seem to be
>opposites. (I would be intrested of hearing of an aplication of the
>above system).
>   Expert Systems is the art of taking human information and encoding
>it into a computer.  While Neural Networks try to devlop there own
>representation of the information.
>
> Any comments ?
This is correct. The term expert system is, however, very often used 
synonomously with knowledge based systems. And quite a lot of these system
will, like ANNs, infer their rules from the data available.

I hope the above wasn't too incoherent, but as I've changed research field now,
I haven't got all that much time too spend spel-checking etc.

Reidar.