Let X be a set of four elements, and let Bx be the set of all
bijective function from X to itself. Clearly, Bx!= none,since the
identity map Ix from x to itself is in Bx. Let B be the set of positive
integers n such that exist f belongs to Bx ,f^n=Ix.
Let n be the smallest element of N. which of the following statements is true?
n= 1,4,6,12
n does not exist because N=none
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答案是12
我想我的問題在於Ix我不知道是什麼碗糕
有大大能夠幫忙提點一下這一題解法嗎?
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