LetsLet's start with a definition:
Definition: A scalar k-th order differential equation on a smooth manifold $M$ ,
is $F(x,v,\frac{\partial {^\left | \sigma \right |}v}{\partial x^\sigma })=0 $
for $\left | \sigma \right |\leqslant k $.
This equation can be viewed as hypersurface
$E=F(x,u,p_\sigma )=0\subset J^kM$ in the space of k-jets . An
An n-dimentionaldimensional integral manifold $L$ of the Cartan distribution is called a multivalued solutionmultivalued solution of equation E, if $L\subset E$.
(see A.G.Kushner Kushner's paper about the classification of monge ampereMonge-Ampère equations)
How can we find the multivalued solution of the equation $\frac{v_{xx}v_{yy}-v_{xy}^{2}}{(1+v_{x}^{2}+v_{y}^{2})^2}=1 $?
How can we find the multivalued solution of the equation $\frac{v_{xx}v_{yy}-v_{xy}^{2}}{(1+v_{x}^{2}+v_{y}^{2})^2}=1 $?