Subject: Fuzzy logic

From: Steven Belknap <[email-masked]>
Date: Sun, 18 Jun 2000 20:38:51 -0500

Fuzzy logic values vary continuously, say from 0 to 1, and thus can 
not be reduced to discrete values without loss of information, unless 
you are at an extrema.

>For example, let's say we give the statement "Foobars like to be
>globbed" a truth value of 0.8 . I would interpret this as either
>
> "80% of foobars like to be globbed"

This is a probabilistic statement about individual foobars, not a 
fuzzy logic statement.

>
>or
>
> "There is 80% certainty that all foobars like to be globbed"

This is a probabilistic statement about the class of foobars, not a 
fuzzy logic statement.

>
>or
>
> "A typical foobar, if asked to express its liking for being globbed on
>a scale from 0 to 1, would give an answer of 0.8"
>
>or some combination of these, all of which are simple true/false
>statements.

If you want to use numbers to indicate the degree of fuzziness, you 
can, although most people use ordinal modifiers like not, slightly, 
moderately, half, mostly, or entirely to indicate the extent of truth.

"Foobars like to be globbed to extent 0.8; foobars do not like to be 
globbed to extent 0.2"

Thus, in fuzzy logic, foobars both like and do not like being 
globbed, the extent to be specified by a number in your example, or 
by some set of ordinal modifiers in most people's lexicon.

-Steven

-- 
Steven Belknap, M.D.
Assistant Professor of Clinical Pharmacology and Medicine
University of Illinois College of Medicine at Peoria