Uniform integrability under continuous functions

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SUMMARY

The discussion centers on the uniform integrability (UI) of the function g(X), where X is a uniform integrable function and g is a continuous function. It is established that g(X) is UI when the support of g is compact, which can be proven using Heine-Borel theorem. The conversation suggests that relaxing the compactness condition may lead to further insights or counterexamples. Additionally, the topic is rooted in introductory measure theory, indicating a foundational understanding of the subject is necessary for deeper exploration.

PREREQUISITES
  • Understanding of uniform integrability in the context of measure theory.
  • Familiarity with continuous functions and their properties.
  • Knowledge of the Heine-Borel theorem regarding compactness.
  • Basic concepts of measure theory, particularly related to functions and integrability.
NEXT STEPS
  • Study the Heine-Borel theorem in detail to understand its implications for compactness.
  • Explore counterexamples to uniform integrability in the context of continuous functions.
  • Research the properties of uniform integrability and its applications in measure theory.
  • Examine the relationship between compactness and uniform integrability in various function spaces.
USEFUL FOR

Mathematicians, particularly those studying measure theory, analysts, and anyone interested in the properties of uniform integrability and continuous functions.

jk_zhengli
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Let X be a uniform integrable function, and g be a continuous function. Is is true that g(X) is UI?

I don't think g(X) is UI, but I have trouble finding counter examples.

Thanks.
 
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This statement is true whenever \supp g (You can prove this with Heine Borel) or the range of {X_n} is compact.
Since now you have the compactness relaxed, you can pursue that direction.

Also, the foundation of this question is more towards Intro to Meas. Theory, you may consider re-post in the right domain.
 
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