Re: What about necessary and sufficient causes in fuzzy logic?

david_olmsted@my-dejanews.com
Mon, 21 Sep 1998 20:56:35 +0200 (MET DST)

In article <35F6E473.E6F03CA9@etruscan.li.it>,
fuzzy-mail@dbai.tuwien.ac.at wrote:
> Hi,
>
> in social sciences, boolean techniques of data analysis are used to
> understand the necessary and sufficient causes, or only necessary and so
> on, causes. Now, with fuzzy sets, does nothing change, in the sense
> that, for example, a sufficient cause continues to be the same if a
> certain factor produces a certain effect, indipendently from other
> factors and indipendently from the grade of membership (presence) with
> which it compares, that is low or high? (Even if, by definition, that
> effect can be produced also if our factor is absent). Or is it
> introduced a fuzzy concept of necessity and sufficiency that is we can
> establish, for example, that under a certain grade of membership
> (presence) a cause is partially sufficient or necessary and so on? And
> how can one construct a membership function of presence and absence?
>
> Thanks in advance,
>
> Gianfranco Giuntoli.
>
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>
Gianfranco,

Asynchronous multivalued logic used in circuit design has a related concept
called the validity measure which is given by the width of the signal pulse
while the magnetude(height)of the pulse gives the membership value. Validity
is a continuous measure of the possible to necessary continuum of modal
logic. In circuits if some object is detected for a fleeting moment at some
certainty level for its class definition the question remains: did it really
exist or is it a noise artifact? The greater the signal's valdity the more
likely it is not an artifact.

To use this idea for data analysis I suppose you would have to use a second
number in an ordered pair similar to that used in vectors thus expanding the
dimensionality of the logic.

For more information on asynchronous multivalued logic and see my site at
http://www.neurocomputing.org

Sincerely,
David Olmsted

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