Method With Nonzero Background Potential. Application to Inverse Scattering for the

We generalize a number of formulas of the method for the Schrōdinger equation to the case of nonzero backqround potential. As a corollary we have found the following reciprocity property ot the Faddeev function h: Where h is a non—analytic extension of the scattering amplitude to the complex domain. As an application we prove the uniqueness theorem and give a reconstruction procedure in the inverse scattering problem for the two—dimensional acoustic equation.