Real Analysis – Continuous and Bounded Variation Does Not Imply Absolutely Continuous

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I know that a continuous function which is a BV may not be absolutely continuous. Is there an example of such a function? I was looking for a BV whose derivative is not Lebesgue integrable but I couldn't find one.

Best Answer

The Devil's staircase function does the trick.

Its derivative is almost surely zero with respect to Lebesgue measure, so the function is not absolutely continuous.

See http://mathworld.wolfram.com/DevilsStaircase.html