Abstract. The Dirichlet problem for the Laplacian in a planar multiply connected interior domain bounded by smooth closed curves is considered in the case when the boundary data is piecewise continuous; i.e., it may have jumps in certain points of the boundary. It is assumed that the solution to the problem may not be continuous at the same points. The well-posed formulation of the problem is given, theorems on existence and uniqueness of a classical solution are proved, and the integral representation for a classical solution is obtained. The problem is reduced to a uniquely solvable Fredholm integral equation of the second kind and of index zero. It is shown that a weak solution to the problem does not exist typically, though the classical solution exists.
Introduction.It is known that if the Dirichlet problem for the Laplacian is considered in a planar domain bounded by sufficiently smooth closed curves, and if the function specified in the boundary condition is smooth enough, then the existence of a classical solution follows from the existence of a weak solution. In the present paper we consider the Dirichlet problem for the Laplacian in a planar multiply connected interior domain bounded by closed curves on the assumption that the boundary data is piecewise continuous; i.e., it may have jumps in certain points of the boundary. We look for a solution to the problem which may be discontinuous at these points. We give the well-posed formulation of the problem. We prove that there exists a unique classical solution to this problem and obtain an integral representation for the classical solution in the form of a double layer potential with some additions. Moreover, we reduce the problem to a uniquely solvable Fredholm integral equation of the second kind and of index zero for the density of a potential.In addition, we prove that a weak solution to this problem may not exist. This result follows from the fact that the square of the gradient of the classical solution, basically, is