Finding Partial Limits of a Sequence: A Homework Challenge

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Homework Help Overview

The discussion revolves around finding all the partial limits of a sequence defined by specific recursive relations. The sequence is characterized by its even and odd indexed terms, with the original poster expressing uncertainty about the terminology and the convergence properties of these subsequences.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants explore the convergence of subsequences, questioning the monotonicity of even and odd indexed terms. There is an attempt to prove the existence of supremums for these sequences, alongside discussions about potential mistakes in calculations and the implications of those errors.

Discussion Status

The discussion includes attempts to clarify the definitions and properties of the sequences involved. Some participants have provided guidance on calculating terms of the sequence to aid understanding. However, there is no explicit consensus on the proof of convergence or supremums, and the original poster has indicated a resolution to their inquiry.

Contextual Notes

There is mention of confusion regarding the notation used in the sequence definitions, as well as the original poster's struggle with proving certain properties of the subsequences. The discussion reflects the challenges inherent in analyzing recursive sequences and their limits.

estro
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Homework Statement


I have to find all the partial limits {I hope this is how this term named in English} of a sequences

Homework Equations


[tex]a_1=0[/tex]

[tex]a_{2n}=\frac {a_{2n-1}} {3}[/tex]

[tex]a_{2n+1} = 1/3 + a_{2n}[/tex]

The Attempt at a Solution


I have tried to prove first that sequences of all the even terms converges due to fact that sequence is monotonic and have a suprimum, but have failed to prove it.
Another problem is that subsequences of odd term is non monotonic, but I also can't use the Cantor's Lemma.

Could you please suggest how to approach this problem?
Thanks.
 
Last edited:
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estro said:

Homework Statement


I have to find all the partial limits {I hope this is how this term named in English} of a sequences


Homework Equations


[tex]a_1=0[/tex]

[tex]a_{2n}=\frac {a_{2n-1}} {3}[/tex]

[tex]a_{2n+1} = 1/3 + 2_{2n}[/tex]
In the equation above do you mean a2n+1 = 1/3 + 22n?
estro said:

The Attempt at a Solution


I have tried to prove first that sequences of all the even terms converges due to fact that sequence is monotonic and have a suprimum, but have failed to prove it.
Another problem is that subsequences of odd term is non monotonic, but I also can't use the Cantor's Lemma.

Could you please suggest how to approach this problem?
Thanks.
 
Sorry, have fixed it in my first post.
 
You're looking at the two subsequences: one with the odd-index terms and the other with the even-index terms. Have you calculated the first dozen or so terms of your sequence?
 
I've calculated again some terms of the sequence and found out that I did a mistake in my previous calculation as both subsequences seem to be monotonic, but I can't find a way to prove that the sequences have suprimums.

0, 0, 81/243, 27/243, 108/243, 36/243, 36/243, 117/243, 39/243, 120/243, 40/243, 121/243
 
I have figured it out, thanks.
 

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