作者iamagine (A-gine)
看板Math
標題[分析] continuous function & compact set
時間Thu Jul 9 22:13:36 2009
Theorem: Let n,m € |N .
If H is compact in |R^n and f : H → |R^m is continous on H,
then f(H) is compact in |R^m.
問題一:
如果改成...
Let H is a subset of |R^n
If K is compact in |R^m and f : H → |R^m is continous on H,
then (
f^-1)(H) is compact in |R^n ?
↑ inverse image
這樣是不是就錯了?
麻煩大大跟我說個反例>""<
問題二:
Let the function f : |R^n → |R^n such that f(K) is compact
whenever K is compact subset of |R^n.
Must f be continuous?
麻煩大大們了>""<
謝謝大家~
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◆ From: 125.224.40.230
推 kerkerkid:問題一的K哪來的... 07/09 22:20
→ kerkerkid:第一題是f^-1(K)吧??... 07/09 22:55
大大對不起>""< 我太笨了,打錯>""<
就像大大說的,我想問的是(f^-1)(K) 才對>""<
※ 編輯: iamagine 來自: 125.224.36.139 (07/10 23:14)
※ 編輯: iamagine 來自: 125.224.36.139 (07/10 23:33)