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wangmabel

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[求助] 测度 已有1人参与

构造一个只包含[0,1]中的无理数的闭集F, 且要求F的测度>0
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wangmabel

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4楼: Originally posted by hank612 at 2014-10-06 23:18:50
It is very easy. Arrange the rational numbers in  as a1,a2,....
Then delete from  the open interval (open ball) centered at ak with radius
B/2^k. B is a small positive number you wish.

This set ...

非常感谢!
5楼2014-10-07 07:49:40
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Edstrayer

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方寸斗室小天地正气迷漫大世界

参看周民强《实变函数》page60Ex3的解答
青葱岁月圣诞夜,浪漫歌舞迎新年。
2楼2014-10-06 17:46:51
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wangmabel

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2楼: Originally posted by Edstrayer at 2014-10-06 17:46:51
参看周民强《实变函数》page60Ex3的解答

请问你有这本书的解答吗?可以发给我吗?
3楼2014-10-06 18:02:45
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hank612

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【答案】应助回帖

★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★
感谢参与,应助指数 +1
wangmabel: 金币+15, ★★★很有帮助 2014-10-07 07:49:06
It is very easy. Arrange the rational numbers in [0,1] as a1,a2,....
Then delete from [0,1] the open interval (open ball) centered at ak with radius
B/2^k. B is a small positive number you wish.

This set meets your need, as
(1) only irrational numbers are left
(2) measure is at least (1-b)
(3) its complement is an open set, thus itself is closed
We_must_know. We_will_know.
4楼2014-10-06 23:18:50
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