Re: misunderstanding positive set theory?

On Thu, 21 Aug 2008 dan.ms.chaos@xxxxxxxxx wrote:

http://www.seop.leeds.ac.uk/symbols/entities.html#Set

I'm using Firefox 2 , Windows Xp . Didn't know about the Unicode
problem . Thought using symbols from
set theory and mathematical logic would make life easier :P .

It doesn't.

B = { a | a in a }

B = { x | x in x }

Y = { Z | for every x , (x is B) or (x in Z) } (logical or , x
can be both in B and Z )

Do you mean 'is' or 'in'. I've assumed 'is'.

Y = { a | for all x, (x = B or x in a) }
.. . = { U, U - {B} } where U is the universe set of all sets.

C = { p | for every element A of Y , p is in A }

C = { a | for all x in Y, a in x }
.. . = /\Y = U - {B}

According to the wikipedia article C , Y , B should be valid in
positive set theory , I think .
However , isn't C = { p | p not in p } ? .

No.
.

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