lebesgue measurable

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Definition

Lebesgue Measurable

A set ER is Lebesgue measurable if for all AR we have

m(A)=m(AE)+m(AEc)

Note

Since for all A,E we have A=(AE)(AEc), we have by subadditivity that m(A)m(AE)+m(AEc).

Thus E is measurable if m(AE)+m(AEc)m(A)

( we only need to show one side of the inequality )

Facts

Theorem

The empty set and the set of real numbers R are measurable. And a set E is measurable if and only if Ec is measurable.

Proof

These are readily verifiable from the definition of measurability - which is symmetric in E and Ec.

References

References

See Also

Mentions

Mentions

File Last Modified
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Created 2025-06-17 Last Modified 2025-07-14