Re: number of membership functions...

Jon Williams (jon@williams-home.demon.co.uk)
Sun, 14 Jun 1998 19:44:12 +0200 (MET DST)

In article <3.0.5.32.19980511151855.007b1670@engr.LaTech.edu>, Hasan R.
Haznedaroglu <hasanh@coes.LaTech.edu> writes
>I remember reading a passage about the number of
>membership functions (MFs) that should be used
>(or recommended) during fuzzy reasoning, in Constantin
>von Altrock's book. The recommended number was about
>(if I'm not wrong) 7 for each variable. The reason
>for using such a low number was that humans can use
>only few linguistic terms simultaneously during their
>reasoning or decision making processes.

This point is specificaly discussed by L.Godo, R.Lopez de Mantaras, C.
Sierra and A Verdaguer 1989. MILORD: The Architectiure and management of
Lingiustically expressed Uncertainty. Intenational Journal of
Intelligent Systems Vol. 4, pp 471- 501.

They refer to the results of Miller, G.A. 1956. The Magical Number Seven
Plus or Minus Two: Some Limits on Our Capacity for processing
Information. Pscychological Review, Vol 63, pp 81 -97.

and conclude that it is unlikely that a person would use more than nine
different linguistic terms to describe the values taken by a variable.

-- 
Jon Williams
e-mail  home    jon@williams-home.demon.co.uk
        college J.Williams@coventry.ac.uk

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