Does Convergence in Measure Always Guarantee Almost Uniform Convergence?

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The discussion confirms that if a sequence of measurable functions converges in measure, it is indeed possible to find a subsequence that converges almost uniformly across all measure spaces. This conclusion is supported by the F. Riesz convergence theorem, which establishes the relationship between convergence in measure and almost uniform convergence. The essential supremum of the difference between the functions approaches zero, but this is distinct from convergence in L^\infty.

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Thorn
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If a sequence of measurable functions (real-valued) converges in measure, is it true that you can find a subsequence that converges almost uniformly? (This is obviously true if m*(domain) is finite...but in general is it?) If so, can someone outline a little why?
 
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Does the almost uniform convergence mean that the essential supremum of f-f_n approaches zero?

If so, I think I came up with a very simple counter example to your claim that m*(domain)<oo would be enough for this.
 
jostpuur said:
Does the almost uniform convergence mean that the essential supremum of f-f_n approaches zero?
No, the usual definition goes something like this: f_n \to f almost uniformly if for every \epsilon &gt; 0 there is a set E of measure less than \epsilon such that f_n \to f uniformly on the complement of E.

This is not the same as convergence in L^\infty.

What the OP is asking turns out to be true, for all measure spaces. It follows from a result that's sometimes called the "F. Riesz convergence lemma/theorem".
 

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