This book is devoted to the mathematical foundation of boundary integral
equations. The combination of ?nite element analysis on the boundary
with these equations has led to very e?cient computational tools, the
boundary element methods (see e.g., the authors [139] and Schanz and
Steinbach (eds.) [267]). Although we do not deal with the boundary
element discretizations in this book, the material presented here gives
the mathematical foundation of these methods. In order to avoid over
generalization we have con?ned ourselves to the treatment of elliptic
boundary value problems. The central idea of eliminating the ?eld
equations in the domain and - ducing boundary value problems to
equivalent equations only on the bou- ary requires the knowledge of
corresponding fundamental solutions, and this idea has a long history
dating back to the work of Green [107] and Gauss [95, 96]. Today the
resulting boundary integral equations still serve as a major tool for
the analysis and construction of solutions to boundary value problems.