Does Everywhere Implies Almost Everywhere

measure-theoryreal-analysis

I know the concept of 'almost everywhere' in measure theory. For example, $f:E\to\mathbb{R}$ is bounded almost everywhere means if $B = \{x\in E: f \text{ is not bounded}\}$, then the measure $\mu(B) = 0$. However, I was wondering if $f$ is bounded implies $f$ is bounded almost everywhere. It seems trivially true to me, but I haven't found any discussions related to this. My purpose is to manipulate the measure concept to help with one of my ongoing proofs.

Thanks very much in advance.

Best Answer

(To get it off the unanswered question queue:)

If $f$ is everywhere bounded, $B=\emptyset$ so $\mu(B)=0$ and you're done.

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