Elliptic equations in a two- or three-dimensional bounded domain may
have singular solutions from the non-smoothness of the domain, changes
of boundary conditions, and discontinuities, singularities of the
coefficients. These singularities give rise to various difficulties in
the theoretical analysis and in the development of numerical algorithms
for these equations. On the other hand, most of the problems arising
from physics, engineering, and other applications have singularities of
this form. In addition, the study on these elliptic equations leads to
good understandings of other types of PDEs and systems of PDEs. This
research, therefore, is not only of theoretical interest, but also of
practical importance. This book includes a-priori estimates
(well-posedness, regularity, and Fredholm property) for these singular
solutions of general elliptic equations in weighted Sobolev spaces, as
well as effective finite element schemes and corresponding multigrid
estimates. Graduate students and researchers will find it a very useful
introductory reference.