Inserted: 21 jan 2010
Last Updated: 24 jun 2013
Journal: Indiana Univ. Math. J.
We regard one side of the coarea formula as a measure and compute its density by an area-type formula. As an application, we show the first nontrivial example of coarea formula for vector-valued sub-Riemannian Lipschitz mappings.
Keywords: coarea formula, Heisenberg groups, implicit function theorem