These Proceedings form a record of the lectures presented at the
interna- tional Conference on Functional Analysis and Approximation held
at the Ober- wolfach Mathematical Research Institute, August 9-16, 1980.
They include 33 of the 38 invited conference papers, as well as three
papers subsequently submitted in writing. Further, there is a report
devoted to new and unsolved problems, based on two special sessions of
the conference. The present volume is the sixth Oberwolfach Conference
in Birkhauser's ISNM series to be edited at Aachen *. It is once again
devoted to more significant results obtained in the wide areas of
approximation theory, harmonic analysis, functional analysis, and
operator theory during the past three years. Many of the papers
solicited not only outline fundamental advances in their fields but also
focus on interconnections between the various research areas. The papers
in the present volume have been grouped into nine chapters. Chapter I,
on operator theory, deals with maps on positive semidefinite opera-
tors, spectral bounds of semigroup operators, evolution equations of
diffusion type, the spectral theory of propagators, and generalized
inverses. Chapter II, on functional analysis, contains papers on modular
approximation, interpolation spaces, and unconditional bases.