Total lightcone curvatures of spacelike submanifolds in   Lorentz-Minkowski space
  We introduce the totally absolute lightcone curvature for a spacelike submanifold with general codimension and investigate global properties of this curvature. One of the consequences is that the Chern-Lashof type inequality holds. Then the notion of lightlike tightness is naturally induced. 
Shyuichi Izumiya
math.DG