1 . 由无理数引发的数学危机一直延续到19世纪,直到1872年,德国数学家戴德金从连续性的要求出发,用有理数的“分割”来定义无理数(史称戴德金分割),并把实数理论建立在严格的科学基础上,才结束了无理数被认为“无理”的时代,也结束了持续2000多年的数学史上的第一次大危机.所谓戴德金分割,是指将有理数集
划分为两个非空的子集M与N,且满足
,
,M中的每一个元素小于
中的每一个元素,则称
为戴德金分割.试判断下列选项中,可能成立的是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316ecb1589c3cc179e2f62507020771e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/252b52fe186ca8f10398dcd32e9ce394.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb4a195a4245b05754edb54660eccc9b.png)
A.![]() ![]() |
B.M没有最大元素,N有一个最小元素 |
C.M有一个最大元素,N有一个最小元素 |
D.M没有最大元素,N也没有最小元素 |
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解题方法
2 . 设
为非空集合,定义
(其中
表示有序对),称
的任意非空子集
为
上的一个关系.例如
时,
与
都是
上的关系.设
为非空集合
上的关系.给出如下定义:①(自反性)若对任意
,有
,则称
在
上是自反的;②(对称性)若对任意
,有
,则称
在
上是对称的;③(传递性)若对任意
,有
,则称
在
上是传递的.如果
上关系
同时满足上述3条性质,则称
为
上的等价关系.任给集合
,定义
为
.
(1)若
,问:
上关系有多少个?
上等价关系有多少个?(不必说明理由)
(2)若集合
有
个元素
,
的非空子集
两两交集为空集,且
,求证:
为
上的等价关系.
(3)若集合
有
个元素
,问:对
上的任意等价关系
,是否存在
的非空子集
,其中任意两个交集为空集,且
,使得
?请判断并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/928008f619c199d9375b03b63f17f0c1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/248bff56f76fc98ac9e16b2c751bc142.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/256b72e8048ad33ee1f6919b04b70ab7.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4fa7f541be676dee0b2f9ec7ad965db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
(2)若集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce642b73be99b3c1a8c5dd38ec58eb28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9434f864089388016b3125ac2b0e0185.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e83ac2d6c698a0ce0dce45a8682a5532.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43e1bef74b304061b73a02892bbf3449.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
(3)若集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce642b73be99b3c1a8c5dd38ec58eb28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9434f864089388016b3125ac2b0e0185.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e83ac2d6c698a0ce0dce45a8682a5532.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43e1bef74b304061b73a02892bbf3449.png)
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3 . 设集合
,集合
,如果对于任意元素
,都有
或
,则称集合
为
的自邻集.记
为集合
的所有自邻集中最大元素为
的集合的个数.
(1)直接判断集合
和
是否为
的自邻集;
(2)比较
和
的大小,并说明理由;
(3)求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db8d9e00ef22cd220a6bbd291f280a83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84cd2449f6ae27a72287be95a661d8f2.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3cfeacc29e6a61c5b3b4e439c0a91df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
(1)直接判断集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4047b80385ef60ea5e9a1f184e7b948b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecde0085a473948c061942a1728a37c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5002f030017f6f0b34a61b2e15c5a9cb.png)
(2)比较
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64927a98d33b49dc5c6a0e65e5e8eb53.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b41788e238eff245e567b58dea3a0003.png)
(3)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/293bd318a7a3796d3589db25148be688.png)
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4 . 已知集合
并且
.定义
(例如
).
(1)若集合
,集合A的子集N满足:
,且
,求出一个符合条件的N;
(2)对于任意给定的常数C以及给定的集合
,求证:存在集合
,使得
,且
;
(3)若集合
满足:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e8aefbf5a9ea3701a4dde426213195f.png)
,其中实数a,b为给定的常数,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/674b35842f32971bc18c2daf361fb194.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0704f453b2de48d36911f7db496bbf82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aa8837b39dc626be5a4bd655997cddf4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0b754788902ab8975c09e567c72025d.png)
(1)若集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f697f48c4c400e08556d8438e5df550c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e3b83ccd27fced5b6f12d4737d0f92a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76136d2926cf8d027df0687aafc55421.png)
(2)对于任意给定的常数C以及给定的集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ea7fcdb5423c1c8c032a3efcf245682.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c7bb58dca886fc65d874e2b30040c02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2ee84c75daf9e8b4a0e13f83b183a16.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4790936ed4b8732f98cd48ad14b84734.png)
(3)若集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f6fe7689c41e590f6910e82c0a5d2cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e8aefbf5a9ea3701a4dde426213195f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ca2ebb5a4ad0586523d56c4f64dce76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/adc250de2317c83a904f0ebce5fc2989.png)
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5 . 已知集合
,若对于任意
,存在
,使得
,则称集合
是“垂直对点集”.则下列四个集合是“垂直对点集”的为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2b392b98ebc75d96d89422ac4f17d0d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/355c6295d218cd43e397064c7dcc19c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87d40d7bb263b5d955f45b08fc18b102.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1da3ff6f17be99ec311610efa08ba002.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
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