- Thread starter
- #1

- Thread starter Fermat
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- Thread starter
- #1

- Jan 29, 2012

- 1,151

You are given, then, that (0, a) and (0, b) are measurable and you can write (a,b)= (0, b)\ (0, a).

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- #3

- Feb 7, 2012

- 2,740

Not quite, there are two things wrong here. First, in a sigma-algebra, you must useI am trying to show that an open set in [0,1] is measurable, given that [0,x] is measurable set for each x in [0,1]. So I need to show (a,b) is measurable. Using the fact that measurable sets form a sigma algebra, I have managed to show that (a,b] is measurable. So (a,b+t] is measurable for any t>0. letting t ->0, can I then conclude that (a,b) is measurable?

What you need to do is to take the