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Topic: Using classes instead of sets
Replies: 26   Last Post: Apr 1, 2013 8:04 PM

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Frederick Williams

Posts: 2,164
Registered: 10/4/10
Re: Using classes instead of sets
Posted: Mar 28, 2013 6:20 PM
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Frederick Williams wrote:
>
> [...] But the language of set
> theory allows x \in x as a formula, but it doesn't allow {x | x in x} as
> a set.


Rubbish. That is the empty set. Maybe I was thinking "it doesn't allow
{x | x not in x} as a set."

--
When a true genius appears in the world, you may know him by
this sign, that the dunces are all in confederacy against him.
Jonathan Swift: Thoughts on Various Subjects, Moral and Diverting



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