Canonical Coordinates and Natural Equation for Lorentz Surfaces in R13

We consider Lorentz surfaces in R13 satisfying the condition H2−K≠0, where K and H are Gaussian curvature mean curvature, respectively, call them of general type. For this class surfaces, we introduce special isotropic coordinates, which canonical, show that coefficient F first fundamental form H, expressed terms canonical satisfy a integro-differential equation natural Using equation, prove theorem Bonnet type for cases constant non-zero minimal surfaces. Finally, give examples illustrating developed theory.