ƫ΢�ַ���Partial differential equations ���ݺ���

����This textbook is intended for students who wish to obtain an introduction to the theory of partial differential equations ��PDEs�� for short���� in particular�� those of elliptic type. Thus�� it does not offer a comprehensive overview of the whole field of PDEs�� but tries to lead the reader to the most important methods and central results in the case of elliptic PDEs. The guiding question is how one can find a solution of such a PDE. Such a solution will�� of course�� depend on given constraints and�� in turn�� if the constraints are of the appropriate type�� be uniquely determined by them. We shall pursue a number of strategies for finding a solution of a PDE�� they can be informally characterized as follows��