[分析] disconnected的定義
我查了兩本書 兩本定義不太一樣
第一本的定義
Let (X,d) be metric space , we say a subset S of X is disconnected if and only if
there exists two disjoint nonempty open subsets H and K of S
such that S = H∪K.
第二本定義
Let (X,d) be metric space , A subset S of X is disconnected if and only if
there exist open sets U and V in (X,d) such that U∩S,V∩S≠ψ,
(U∩S)∩(V∩S)＝ψ and (U∩S)∪(V∩S)＝S.
請問可以解釋一下定義嗎? 謝謝!
圖解:http://ppt.cc/XozW
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