→ keroro321 :for any map g:|N->|N ,((s。g)^(-1))(1) = ? 09/28 14:31
推 recorriendo :left inverse只需要把2變回1 3變回2... 至於1可以變 09/28 14:45
→ recorriendo :到任何數 沒有right inverse是因為他不surjective 09/28 14:45
題目是這樣的....
|N={1,2,3,...} is nature number, and let s:|N -->|N be the shift
map, defined by s(n)=n+1.
Prove that s has no right inverse, but that is has infinitely
many left inverses.
這題想好久，不知道該從何下手....
煩請各位大大的指教了 :)
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