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FACTORIALS OF INFINITE CARDINALS IN ZF PART I: ZF RESULTS
The Journal of Symbolic Logic ( IF 0.5 ) Pub Date : 2019-11-04 , DOI: 10.1017/jsl.2019.74 GUOZHEN SHEN , JIACHEN YUAN
The Journal of Symbolic Logic ( IF 0.5 ) Pub Date : 2019-11-04 , DOI: 10.1017/jsl.2019.74 GUOZHEN SHEN , JIACHEN YUAN
For a set x , let ${\cal S}\left( x \right)$ be the set of all permutations of x . We prove in ZF (without the axiom of choice) several results concerning this notion, among which are the following:(1) For all sets x such that ${\cal S}\left( x \right)$ is Dedekind infinite, $\left| {{{\cal S}_{{\rm{fin}}}}\left( x \right)} \right| < \left| {{\cal S}\left( x \right)} \right|$ and there are no finite-to-one functions from ${\cal S}\left( x \right)$ into ${{\cal S}_{{\rm{fin}}}}\left( x \right)$ , where ${{\cal S}_{{\rm{fin}}}}\left( x \right)$ denotes the set of all permutations of x which move only finitely many elements.(2) For all sets x such that ${\cal S}\left( x \right)$ is Dedekind infinite, $\left| {{\rm{seq}}\left( x \right)} \right| < \left| {{\cal S}\left( x \right)} \right|$ and there are no finite-to-one functions from ${\cal S}\left( x \right)$ into seq (x ), where seq (x ) denotes the set of all finite sequences of elements of x .(3) For all infinite sets x such that there exists a permutation of x without fixed points, there are no finite-to-one functions from ${\cal S}\left( x \right)$ into x .(4) For all sets x , $|{[x]^2}| < \left| {{\cal S}\left( x \right)} \right|$ .
中文翻译:
ZF 第一部分中无限红衣主教的因子:ZF 结果
对于一套X , 让${\cal S}\left(x\right)$ 是所有排列的集合X . 我们在 ZF(没有选择公理)中证明了关于这个概念的几个结果,其中包括:(1)对于所有集合X 这样${\cal S}\left(x\right)$ 是戴德金无限的,$\左| {{{\cal S}_{{\rm{fin}}}}\left( x \right)} \right| < \左| {{\cal S}\left( x \right)} \right|$ 并且没有从${\cal S}\left(x\right)$ 进入${{\cal S}_{{\rm{fin}}}}\left( x \right)$ , 在哪里${{\cal S}_{{\rm{fin}}}}\left( x \right)$ 表示所有排列的集合X 它只移动有限多个元素。(2) 对于所有集合X 这样${\cal S}\left(x\right)$ 是戴德金无限的,$\左| {{\rm{seq}}\left( x \right)} \right| < \左| {{\cal S}\left( x \right)} \right|$ 并且没有从${\cal S}\left(x\right)$ 进入序列(X ), 其中 seq (X ) 表示所有元素的有限序列的集合X .(3) 对于所有无限集X 使得存在一个排列X 没有不动点,就没有有限对一的函数${\cal S}\left(x\right)$ 进入X .(4) 对于所有集合X ,$|{[x]^2}| < \左| {{\cal S}\left( x \right)} \right|$ .
更新日期:2019-11-04
中文翻译:
ZF 第一部分中无限红衣主教的因子:ZF 结果
对于一套