http://www.artofproblemsolving.com/Forum/viewtopic.php?f=70&t=13870&
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◆ From: 61.217.231.5
是否存在如此的函數 f:|R->|R .
(i) f is additive . (i.e. , f(x+y) = f(x)+f(y) )
(ii) For any nonempty open interval I = (a,b) , f(I)=|R .
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有興趣可以想一下 , 解答在這論壇的2F .