What do the measures mean?

Stefan van den Oord (s.m.vandenoord@student.utwente.nl)
Wed, 21 Oct 1998 11:56:36 +0200 (MET DST)

Hello,

For quite some time I've been thinking about different kinds of
uncertainty and about the different theories and measures for it.

I think there are three kinds of uncertainty: chance, possibility and
certainty. Let me illustrate this with an example. I see a (Dutch)
person who I do not know. Because of my (statistical) knowledge that of
all Dutch people there is always a (not very large) part that is ill,
there is a small chance that this person I see is ill. However, the
possibility that he is ill is one; I don't have proof that he is not
ill. The certainty that he is ill is zero, again because I have no proof
of it. (If I do have proof, the possibility remains one, but the
certainty becomes more than zero.)

These three concepts are modeled by probability theory (chance) and
possibility theory (possibility and certainty). Why do we need fuzzy set
theory, and if we do, what is the meaning of the fuzzy membership
degree? What do you think about this?

Greetings,

Stefan van den Oord

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