Can You Visualize the Definition of Lim Inf Using a Simple Example?

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SUMMARY

The discussion centers on the concept of "lim inf" (limit inferior) in the context of two sequences, {xn} and {yn}. A participant references the Bolzano-Weierstrass theorem, asserting that the limit inferior of a sequence is less than or equal to the limit of its subsequence, denoted as x_{N_n}. The conversation highlights a misunderstanding regarding the term "bounded series" in relation to the sine function, clarifying that it is a function rather than a series or sequence. A request for a visual example to illustrate the relationship between lim inf and limits is made, emphasizing the need for clearer connections between these mathematical concepts.

PREREQUISITES
  • Understanding of sequences and subsequences in mathematical analysis.
  • Familiarity with the Bolzano-Weierstrass theorem.
  • Knowledge of limit concepts, specifically limit inferior (lim inf).
  • Basic comprehension of functions and their properties, particularly bounded functions.
NEXT STEPS
  • Study the formal definition and properties of limit inferior in mathematical analysis.
  • Explore visual representations of sequences and their subsequences using graphing tools.
  • Learn about the Bolzano-Weierstrass theorem and its implications for bounded sequences.
  • Investigate examples of bounded functions, such as y = sin(x), and their limits.
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Students and educators in mathematics, particularly those studying real analysis, as well as anyone seeking to deepen their understanding of limits and subsequences in mathematical sequences.

transgalactic
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my question and where i got stuck in the solution are in this link:

http://img244.imageshack.us/img244/5316/84661104oi7.gif
 
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You have two sequences {xn} and {yn} and say that "by Bolzano-Weierstrasse", [itex]\underline{\lim_{n\rightarrrow \infty}x_n}\le \lim_{n\rightarrow\infty}x_{N_n}[/itex].

I will guess, from your other posts, that the underline is meant to be "lim inf" but what is [itex]x_{N_n}[/itex]? An arbitrary subsequence of the sequence? If so, that would appear to follow directly from the definition of "lim inf" as the infimum of the set of all subsequential limits.

You then refer to the "bounded series y= sin(x)" which is neither a series nor a sequence but a function.
 
so the lim inf is the infimum of the limits of all the sub sequences

can you give a visual example that shows that

lim inf Xn<=lim Xn by that lim inf definition

i can't link them together

??
 
Last edited:

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