On 8/20/2017 12:28 AM, Rustom Mody wrote:
Lives today in python in the fact that the russel-set gives a straightforward
syntax error and nothing more grandly profound
R = {x if x not in x}
R = {x for x not in x}
Try the actual Python syntax set builder expression and you get
executable code:
sos = <some 'set of sets'>
R = {x for x in sos if x not in x}
In Python, the expression creates a new set that is not a member of sos,
so the x in 'x not in x' is never S, and there is no problem, as far as
S is concerned, in evaluating 'x not in x'.
But, is R is equal to some set z in sos? If yes, then we could identify
R and z and say that R is in sos. But the answer is No. Russell's
'paradox' comes from separately insisting that the answer is also Yes.
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