ABSTRACT
In this chapter, we study elliptic problems on manifolds with edges. Let us explain why such studies are important. So far, we have considered only elliptic operators, but it often happens that even though the interior symbol of an edge-degenerate operator is elliptic, the edge symbol is not invertible and the operator fails to be Fredholm. (An example to that effect can be found in the first section of this chapter.) At the same time, we always require that the conormal symbol of the edge symbol be invertible, so that the edge symbol itself is Fredholm.
