Mistake in my analysis book ? Or am I missing something ?

Click For Summary

Homework Help Overview

The discussion revolves around the properties of bounded sets in the context of real analysis, specifically addressing the implications of the Bolzano-Weierstrass theorem and uniform continuity on closed intervals.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the conditions under which limits of sequences can exist outside of a bounded set, questioning the definitions and properties of open versus closed sets.

Discussion Status

Some participants have provided insights into the nature of bounded sets and their limits, noting that a bounded set does not necessarily have to be closed. There is an ongoing exploration of the implications of these properties without a clear consensus.

Contextual Notes

Participants are considering the definitions of bounded and closed sets, as well as the specific theorems mentioned, which may influence their understanding of the problem.

╔(σ_σ)╝
Messages
839
Reaction score
2

Homework Statement



Please review the attachment.

Why can L be OUTSIDE of D ?

x_n \in D and D is bounded. So doesn't that mean that any subsequential limit of x_n has to be in D ? Btw, Theorem 3.10 is Bolzano Weierstrass.
Theorem 4.4 Says that A continuous function on a closed interval is uniformly continuous there.
 

Attachments

  • DSC_0025.jpg
    DSC_0025.jpg
    50.7 KB · Views: 378
Last edited:
Physics news on Phys.org
I think I understand now.

They said that D is bounded by not closed. i.e suppose D = (a,b)

x_{n_k} \to a could happen and a in not in D.

Is this correct ? Anyone ?
 
What you said is right. Also, the bounded subset need not be an interval of reals; for example, the subset could be all the rational numbers from 0 to 2. Then there are an uncountable number of points not in the set that are the limit of Cauchy sequences inside the set.
 
Perfect. Thanks.
 

Similar threads

  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
6
Views
2K