Model examples of sub-Lorentzian structures will be considered and a new form of the co-area formula for functions will be derived.
Sub-Lorentzian structures are a sub-Riemannian generalization of Minkowski's geometry, and the latter, in turn, can be considered a geometric interpretation of the space-time of the special theory of relativity. The study of such structures has become relevant since the beginning of the 2000s, in particular, geodesics and the connection with the description of the motion of a relativistic particle in a constant uniform electromagnetic field were studied on them. In turn, the co-area formula is important in deriving the properties of classes of extreme surfaces, which until recently were practically not studied on sub-Lorentzian structures. The form of the co-area formula derived in the framework of the mini-course is new for the classical geometry of Minkowski, which opens up new possibilities for the formulation and solution of new problems in both this geometry and its generalizations.