Localization for the discontinuity line of the right-hand side of a differential equation

We propose a new approach to the study of inverse problems for differential equations with constant coefficients. Its application is illustrated by the example of one partial differential equation with three independent variables. The right-hand side of the equation is assumed to be a discontinuous function of space variables. The inverse problem is to find some hull containing the discontinuity line of the right-hand side. An algorithm for constructing such a hull is obtained: it is a square whose sides are tangent to the discontinuity line.