[分析] Royden 習題

看板Math作者 (醉翁之意)時間14年前 (2011/10/23 22:20), 編輯推噓7(706)
留言13則, 6人參與, 最新討論串1/8 (看更多)
Ch2. 18. Let E have finite outer measure. Show that there is an F_sigma set F and a G_delta set G s.t. F is included in E, E is included in G, and m*(F)=m*(E)=m*(G). G_delta部分幾乎跟課本定理證明一樣,所以已經解決,剩下 F_sigma部分。 23. For any set A, define m***(A) = sup {m*(F) | F is closed and included in A.} . How is m*** related to m* ? 我認為應該是 m*** = m*,我想本題的關鍵應該與18題我不會做的部分一樣。 目前有做出一個方向: m***(A) - ε < m*(F) ≦ m*(A) implies m***(A)≦ m*(A). 令一個方向要請教各位高手。 感激不盡! -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 122.117.200.15

10/23 22:44, , 1F
1. 取 complement
10/23 22:44, 1F

10/23 22:52, , 2F
好像不行XD..你是在抽象的 measurable space 嗎??
10/23 22:52, 2F

10/23 23:55, , 3F
應該在R^n吧 才有拓撲
10/23 23:55, 3F

10/24 00:47, , 4F
23. 若 m*(A)<∞, 則 A可測 <=> m***(A) = m*(A)
10/24 00:47, 4F

10/24 00:54, , 5F
對任意的 A, m***(A)≦ m*(A)
10/24 00:54, 5F

10/24 02:27, , 6F
1拓撲處處都有, 2 Royden 應該都在R^n裡
10/24 02:27, 6F

10/24 08:59, , 7F
在R^n中,可否更詳細些
10/24 08:59, 7F

10/24 09:14, , 8F
measure space 不一定要有 topology
10/24 09:14, 8F

10/24 09:14, , 9F
但沒有 topology 很多東西都不能做
10/24 09:14, 9F

10/24 09:15, , 10F
而且既然提到 F_sigma, G_delta,那就有 topology
10/24 09:15, 10F

10/24 19:35, , 11F
我的意思是說R^n有 sigma-finite, 我只是想知道空間
10/24 19:35, 11F

10/24 19:35, , 12F
有無類似的好性質
10/24 19:35, 12F

11/29 21:02, , 13F
18 題好像錯了XD 要 meaurable才能得證後半部!
11/29 21:02, 13F
文章代碼(AID): #1Ef2AwGT (Math)
文章代碼(AID): #1Ef2AwGT (Math)