>>> John Boone on Fuzzy Logic
WE> Hm. Can you also archive it in a file? May be useful for
WE> inclusion in subsequent discussion.
JB> Yep, but would require me to type and save with some sort
JB> of editor.
Shouldn't. BlueWave offline reader has a save to file feature. My
communication software has a screen capture feature. If you're using windows
you ought to be able to cut and paste a whole message. Additionally, BBS
read messages software may allow a download of messages but this may be
little different than having offline message reading software.
WE> WE> First there is fuzzy set theory in which a set is an
WE> WE> assignment of a degree of belonging to each element. For
WE> WE> simplicity, elements are consider to be distinct from sets.
WE> WE> The second notion is fuzzy logic or multi-value logic
WE> WE> which assigns multiple truth values to statements.
WE> JB> Yes, but I do believe they are related. For example,
WE> JB> when I examine a system of statements, I often use set
WE> JB> theory to help me.
WE> Yes they are. The non-fuzzy propositional 'and', 'or', 'not', and
WE> 'implies' are in parallel with the set multiplication, addition,
WE> complimentation and inclusion. not(x or y) = notx and noty
WE> or -(x + y) = (-x) * (-y) is true for both sets and
WE> propositions. Indeed, the duality theorem of set theory is
WE> a rerun of the duality theorem for the propositional
WE> calculus. However note the difference. Logic will go into
WE> (x)P and (Ex)P while sets are concerned about x e A. For
JB>
JB> Not sure what you mean by (x)P and (Ex)P??????
WE> all x P, there exists a x such that P, x is a member of A.
WE> Here we see divergence.
Let P be the statement (x is weird). Then (x)(x is weird) is 'all is weird'
and (Ex)(x is weird) is 'something is weird', or formally 'for all x, x is
weird' and 'there exists an x such that x is weird'. Note that (x)P is
equivalent to not (Ex)(not P) and (Ex)P is equivalent to not (x)(not P).
Perhaps I should write P(x) for 'x has the property P', 'P is true for x',
etc. Then (x)P(x) is 'for all x, P is true of x'.
JB> Are these set statements or propositional statements?
JB> At points such as "x is a member of A" reminds me of
JB> set theory, while "For all x P", leaves me wondering what
JB> P is (the set of Propositional statements)?
They are quantifiers in the sense that 'for all', and 'there exists' quantify
how many. Another quantifier in use is (E!x)P 'there exists exactly one x
such that P'. These are logical statements. They are not part of
propositional calculus, they are included in an extension called quantifier
calculus. P or actually P(x) is a property of x such as 'blue' or 'x is
blue'. When you take a thing, a, and apply a property P to a, just as with a
function, you get P(a) which is a statement (about a). This statement is
true or false according to whether a has the property P or not.
... I think, therefore the universe thinks.
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