Homepage Solution manuals Terence Tao An Introduction to Measure Theory Exercise 1.5.15 (Uniformly integrable but not convergent sequences)

Exercise 1.5.15 (Uniformly integrable but not convergent sequences)

Give an example of uniformly integrable functions that converge pointwise a.e. to zero, but do not converge in measure.

Answers

The only case not covered by the restrictions of the uniform integrability is the escape to horizontal infinity. Let fn := 1[n,n+1]. Then it is easy to verify that (f )n is uniformly integrable. From Example 1.5.2 we now that (f )n converges pointwise to zero, but not uniformly, almost uniformly, in L1 norm nor in measure.

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2020-11-01 00:00
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