查看完整版本 : point set topology新手

go2074 2017-10-11 03:26 PM

point set topology新手

我有2條proof唔知岩唔岩~~
1. prove  {a} is not an open set
2. prove (a,b] is not an open set
我的做法如下

波菜東 2017-10-17 12:28 AM

1.
There exists a in S={a} such that for all open neighbourhood N of a,
N is not a subset of S.

2.
There exists b in S=(a,b] such that for all open neighbourhood N of b,
N is not a subset of S.

14c14c 2017-10-20 02:02 AM

思路正確, 但係你兩題寫到一舊舊咁又撞晒notation, 稱唔上係正確既數學證明
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查看完整版本: point set topology新手