ABSTRACT
The theory of interpolation spaces is a branch of functional analysis which has been applied to a number of areas in analysis, most notably to the theory of partial differential equations. We have in the previous chapter studied Hs Sobolev spaces and traces in Hs since they are “basic tools” in the analysis of boundary value problems. This leads in a natural way to the theory of interpolation of linear operators and function spaces. This theory plays a significant role in obtaining regularity results for boundary value problems.
