I cant understand this liminf/sup definition

  • Thread starter transgalactic
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    Definition
In summary, "sup" is a property of a set and is represented by sup_{n\ge m} {a_n}. This means that the supremum (or highest possible value) of the set {a_m, a_{m+1}, a_{m+2}, ...} is taken over the range of n≥m. This notation does not involve a limit, as it does not contain a -> symbol.
  • #1
transgalactic
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i got this new definition

http://img515.imageshack.us/img515/5666/47016823jz1.gif

what is the meaning of n>=0 under a sup.
sup is not a limit
its only a number
we can't put index under it
what is the meaning of this indexes?
 
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  • #2
transgalactic said:
what is the meaning of n>=0 under a sup.
sup is not a limit
its only a number
we can't put index under it
what is the meaning of this indexes?

Hi transgalactic! :smile:

Under the sup is n ≥ 0, not n -> 0.

anything with a -> (such as n -> 0) would be a limit, as you know …

anything without a -> (such as n ≥ 0) means that that is the range over which the sup is taken …

in other words, if you rewrite it inside {}, then it finishes with : n ≥ 0} :wink:
 
  • #3
i can't imagine what you are saying

can you rewrite the definition
 
  • #4
"sup" is a property of a set. [itex]sup_{n\ge m} {a_n}[/itex] is the supremum of the set {a_m, a_{m+1}, a_{m+2}, ...}.
 

1. What is a liminf/sup?

A liminf/sup, short for limit inferior/superior, is a mathematical concept used to describe the behavior of a sequence of numbers or functions as the sequence approaches infinity. It is the smallest or largest limit point of the sequence, respectively.

2. How do you calculate a liminf/sup?

To calculate a liminf/sup, you first need to determine the set of values that the sequence approaches as it tends towards infinity. Then, the liminf is the smallest value in this set, while the limsup is the largest value.

3. What is the difference between liminf and limsup?

The main difference between liminf and limsup is that liminf is the smallest possible limit point of a sequence, while limsup is the largest possible limit point. Another way to think about it is that liminf is the lowest possible value that the sequence will eventually approach, while limsup is the highest possible value.

4. Why is liminf/sup important in mathematics?

Liminf/sup is important in mathematics because it helps us understand the long-term behavior of sequences and functions. In many cases, the liminf/sup can tell us whether a sequence will eventually converge to a single value or not. It is also useful in analyzing the convergence of series and determining the existence of limits.

5. How can I use liminf/sup in real-world applications?

Liminf/sup has various real-world applications, especially in fields such as engineering, economics, and physics. For example, liminf/sup can be used to predict the long-term behavior of a system, analyze the stability of a structure, or determine the equilibrium point of a chemical reaction. It is also commonly used in data analysis and signal processing to identify trends and patterns in a sequence of data points.

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