Lipschitz Continuity .... and Continuity in R^n ....

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SUMMARY

This discussion centers on the relationship between Lipschitz continuity and continuity in the context of real analysis, specifically referencing "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk. The user, Peter, seeks a rigorous proof that Lipschitz continuity implies continuity and uniform continuity of a mapping f. A participant, GJA, provides a method involving the selection of δ = ε/k, demonstrating that this choice leads to uniform continuity, which Peter confirms as correct.

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  • Understanding of Lipschitz continuity and its mathematical definition
  • Familiarity with the concepts of continuity and uniform continuity
  • Basic knowledge of ε-δ definitions in real analysis
  • Experience with mathematical proofs and rigorous argumentation
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  • Study the definitions and properties of Lipschitz continuity in detail
  • Explore the implications of uniform continuity in real analysis
  • Review examples of mappings that demonstrate Lipschitz continuity
  • Practice constructing rigorous proofs involving ε-δ arguments
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Students of real analysis, mathematicians focusing on continuity properties, and educators teaching advanced calculus concepts will benefit from this discussion.

Math Amateur
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I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ...

I am focused on Chapter 1: Continuity ... ...

In Definition 1.3.4 D&K define continuity and then go on to define Lipschitz Continuity in Example 1.3.5 ... ... (see below for these definitions ...)I have tried to show that Lipschitz Continuity implies continuity of a mapping f ... but have not succeeded ...

Can someone please demonstrate how to rigorously prove that Lipschitz continuity implies that f is continuous ... (***edit*** ... better still would be to show that Lipschitz continuity implies that f is uniformly continuous ...)Help will be appreciated ...

Peter========================================================================================***Note***

D&K's definitions of continuity and Lipschitz continuity read as follows:https://www.physicsforums.com/attachments/7749Peter
 
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Hi, Peter.

For a given epsilon, choose $\delta=\epsilon/k$. Note that the choice of $\delta$ works for all $x$, which implies uniform continuity.
 
GJA said:
Hi, Peter.

For a given epsilon, choose $\delta=\epsilon/k$. Note that the choice of $\delta$ works for all $x$, which implies uniform continuity.

Thanks GJA ... ...

I think I can see this ... since then we have ...

$$\mid \mid x - x' \mid \mid \Longrightarrow \mid \mid f(x) - f(x') \mid \mid\le k \mid \mid x - x' \mid \mid = k \delta = \epsilon
$$Is that correct?

Peter
 
You got it!
 

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