Is there a "fractal" set $E \subset \mathbb R^2$ such that the indicator function $\mathbf{1}_E$ is in $BV(\mathbb R^2)$?
1 Answer
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An open subset $E$ of $\mathbb R^{N}$ such that $\mathbf 1_E$ belongs to $BV$ is said to be with "finite perimeter" and this implies that $$ \mathcal H^{N-1}(\partial E)<+\infty, $$ where $\mathcal H^{N-1}$ stands for the $N-1$ Hausdorff measure. Gauss-Green formula holds true for such open sets. As a result, we have in general $$ 0<\mathcal H^{N-1}(\partial E)<+\infty, \text{ which implies for $\epsilon >0$, } \mathcal H^{N-1+\epsilon}(\partial E)=0, \mathcal H^{N-1-\epsilon}(\partial E)=+\infty. $$
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$\begingroup$ I'm not sure what the last statement implies with respect to the question. $\endgroup$– RikuCommented Apr 23, 2019 at 20:56