Can Two Subsequences Converge to 0 and 1 Respectively?

  • Thread starter Thread starter playa007
  • Start date Start date
  • Tags Tags
    Limit
Click For Summary
SUMMARY

The discussion centers on proving that for a bounded sequence {a_n} with subsequential limit points {0, 1}, it is possible to extract two distinct subsequences: one converging to 0 and the other to 1. The proof utilizes the definition of limit points and the bounded nature of the sequence, specifically leveraging the intervals (-ε, ε) and (1-ε, 1+ε) to demonstrate that all but a finite number of terms in {a_n} fall within these ranges. The partitioning of the sequence at the midpoint (1/2) effectively separates the terms into the two required subsequences.

PREREQUISITES
  • Understanding of bounded sequences in real analysis
  • Familiarity with subsequential limits and convergence
  • Knowledge of ε-δ definitions in limits
  • Ability to construct subsequences from a given sequence
NEXT STEPS
  • Study the properties of bounded sequences in real analysis
  • Learn about subsequential limits and their implications
  • Explore ε-δ definitions and their applications in proofs
  • Investigate techniques for constructing subsequences from sequences
USEFUL FOR

Students of real analysis, mathematicians focusing on convergence and limits, and anyone interested in the properties of bounded sequences and subsequences.

playa007
Messages
25
Reaction score
0

Homework Statement


Suppose {a_n} is a bounded sequence who's set of all subsequential
limits points is {0,1}. Prove that there exists two subsequences,
such that: one subsequence converges to 1 while the other converges
to 0, and each a_n belongs to exactly one of these subsequences.


Homework Equations





The Attempt at a Solution


Well, it's clear that at the limit points 0 and 1; there is a subsequence that that converges to it. I'm not quite sure about how to prove that each a_n belongs to exactly one of these subsequences or how to apply the bounded property of {a_n} into this question.
 
Physics news on Phys.org
This will depend slightly on the definition you are using.
Suppose {a_n} is a bounded sequence who's set of all subsequential
limits points is {0,1}
Suppose epps is a positive real number
0 and one are limit points so it is known that
(-eps,eps)U(1-eps,1+eps)
Contains all but a finite number of the a_n
now the sequence can be easily partitioned by
1/2
one subsequence if a_n<=1/2
another if a_n>1/2
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
Replies
4
Views
2K
Replies
6
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K