Finding a Sequence with Limit Set [0,1]

In summary: The article is a bit dense, but it's a pretty good read. In summary, the author shows that since the sequence sin n is non-repeating, then every point in the interval [-1,1] is a cluster point. This is intuitively clear, but the author provides a rigorous proof.
  • #1
PingPong
62
0

Homework Statement


Find a sequence whose set of subsequential limits is the interval [0,1].


Homework Equations


If the sequence does not repeat itself, then any subsequential limit is a cluster point.

The Attempt at a Solution



I've an idea that [itex]|\sin n|[/itex] is a solution to this, but I'm not sure how to prove this.

What I need to show is that, since the sequence I've chosen is non-repeating, then every point in the interval [0,1] is a cluster point. That is, if I take any number in [0,1] and am given an epsilon>0, can I always find an infinite amount of members in the sequence in an epsilon neighborhood around the number? This seems to intuitively work since [itex]|\sin n| [/itex] is all over the interval [0,1] (though not necessarily touching every point in the interval), but can this argument be made more rigorous? Any suggestions?
 
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  • #2
What can the rationals in [0,1] do for you?
 
  • #3
|sin(n)| does almost certainly work. But I don't know an obvious proof of this. Maybe think about an easier example though. How about n*sqrt(2) mod 1? That should be 'all over', too, and maybe easier to deal with. Sorry, but I was just going zzzzz and found your post, so I can't give hints right now.
 
  • #4
morphism said:
What can the rationals in [0,1] do for you?

Works also, and even easier. Nice.
 
  • #5
Thanks Dick and Morphism. I feel really silly now - I was trying to make it much too complicated. Obviously, since the closure of [itex]Q\cap [0,1][/itex] is again [0,1], then the subsequential limits of a sequence of rational numbers in that interval (say, in the order given by the Cantor diagonalization process, throwing away those outside the interval) is the interval itself.

As a side note, in my search for information on cluster points, I stumbled upon an article (on JStor, which my university subscribes to, so I won't post the url since most people won't be able to access) that gives a proof that the cluster points of sin n is the interval [-1,1].
 

What is "Finding a Sequence with Limit Set [0,1]"?

"Finding a Sequence with Limit Set [0,1]" is a mathematical concept where a sequence of numbers is identified that approaches a specific limit within the range of 0 to 1.

Why is it important to find a sequence with limit set [0,1]?

Finding a sequence with limit set [0,1] is important because it helps us understand the behavior of numbers within a specific range. This information can be used in various fields such as physics, engineering, and finance.

What are the steps involved in finding a sequence with limit set [0,1]?

The steps involved in finding a sequence with limit set [0,1] include identifying the given limit, determining the range of numbers (0 to 1), and then finding a pattern or algorithm that produces a sequence of numbers that approaches the given limit within the specified range.

Can any sequence of numbers have a limit set [0,1]?

No, not all sequences of numbers have a limit set [0,1]. Only sequences that approach a specific limit within the range of 0 to 1 can have a limit set [0,1].

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