Find some extraordinary subset of [0,1]

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Homework Help Overview

The problem involves finding a subset A of the interval [0,1] that satisfies the condition A=cl(int A), where cl denotes closure and int denotes interior. Additionally, the boundary of A is required to not have measure zero.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the fat Cantor set as a potential starting point for constructing the desired subset. There are attempts to modify this set, but challenges arise in ensuring the boundary condition is met.

Discussion Status

The discussion is ongoing, with participants exploring various modifications to the fat Cantor set. Some guidance has been offered regarding the use of open intervals and the boundary of the closure of a set, but there is no explicit consensus on the correct approach yet.

Contextual Notes

Participants are grappling with the definitions of closure, interior, and boundary in the context of measure theory, and there is an acknowledgment of the complexity involved in modifying known sets to meet the problem's requirements.

Maclaurin
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Homework Statement


I want to find a subset A of [0,1] such that A=cl(int A) and bd A does not have measure zero where cl means closure and int means interior.

Homework Equations





The Attempt at a Solution



I tried some sets, but failed.
 
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I tried that set but it was difficult for me to modify it. Can you give me more hint?
 
Well, you want the fat Cantor set to be the boundary of the set you want.

Every step you leave out some open intervals. Now let V be the union of the open intervals you leave out at the odd steps. Take \overline{V} to be your set.
 
I think bd of V is not the fat Cantor set... what should I do?
 
ah instead of bd of V, boundary of closure of V.
 

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