作者tryitredboy (dsd)
看板Math
標題[分析] 有關continuous&compact&connected
時間Thu Dec 3 14:17:33 2009
下面幾個小題想找幾個例子
f is continuous
f:R->R
-1
(1) k is compact , but f (k) is not compact
-1
(2) k is connected , but f (k) is not connected
(3) U is open , but f(U) is not open
(4) U is closed , but f(U) is not closed
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