On 2D Inverse Problems/Schrodinger equation

The conductivity equation  
is equivalent to: 
for potential 
For an analog of this system on e-networks, one defines the solution of the Schrodinger equation u on the nodes and the square of the conductivity on the edges by the following formula: <math>\c^2(a,b) = x(a)x(b).
Exercise (**). Reduce the inverse problem for the Schrodinger equation on domain to the conductivity equation one with conductivity c.