 \int_{\partial {{\cal L}}(t)} \frac{g}{\|\nabla f\|}d{{\cal H}}.$$  [**Lemma 0.0.**]{} [*Let $g\, :\, {I\!\!R}^k\to{I\!\!R}_+$ be a borel bounded function and assume that [**H0**]{}, [**H0**]{} hold. Then