Is f(x) uniformly continuous on [0, inf)?

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SUMMARY

The discussion centers on the uniform continuity of the function f defined on the interval [0, ∞). It is established that while f is uniformly continuous on [a, ∞) for some a > 0, this does not guarantee uniform continuity on the entire interval [0, ∞). A counterexample is provided with the piecewise function f(x) = x for x ≥ 1 and f(x) = 1/(x - 1) for x < 1, which demonstrates that the lack of continuity at x = 1 leads to the failure of uniform continuity on [0, ∞).

PREREQUISITES
  • Understanding of uniform continuity in mathematical analysis
  • Familiarity with piecewise functions and their properties
  • Knowledge of limits and continuity in real analysis
  • Basic concepts of function mapping from [0, ∞) to ℝ
NEXT STEPS
  • Study the definition and properties of uniform continuity in detail
  • Explore counterexamples in real analysis to understand limitations of continuity
  • Learn about the implications of continuity on different intervals
  • Investigate other types of continuity, such as pointwise and Lipschitz continuity
USEFUL FOR

Mathematics students, educators, and anyone studying real analysis, particularly those interested in the concepts of continuity and uniform continuity in functions.

Icebreaker
"Suppose f:[0, inf) -> R is such that f is uniformly continuous on [a, inf) for some a>0. Prove that f is uniformly continuous on [0, inf)."

But this is not true, is it? Consider the function

[tex]f(x)=\left\{\begin{array}{cc}x &\mbox{ if }x\geq 1\\ \frac{1}{x-1} &\mbox{ if }x<1\end{array}\right[/tex]
 
Physics news on Phys.org
Hah! The question forgot to state that f is supposed to be a continuous map [itex][0, +\infty) \rightarrow \mathbb{R}[/itex]!
 
Phew! It's not just me then.
 

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