Sub-Lorentzian Coarea Formula for Mappings of Carnot Groups

Abstract

Considering the class of contact mappings of Carnot groupswith a multidimensional sub-Lorentzian structure on the preimages,we prove thatthe tangent plane approximates the level setsto a higher order than in the classical case.We also obtain a coarea formula for such mappingswith a sub-Lorentzian measure on the level sets.