The annual Operator Theory conferences in Timigoara are conceived as a means to promote cooperation and exchange of in formation between specialists in all areas of Operator Theory. The present volume consist of papers contributed by the partici pants of the 1981 Conference. Since many of these papers contain results on the invariant subspace problem or are related to the role of invariant subspaces in the study of operators or operator systems, we thought it appropiate to mention this in the title of the volume, though the "other topics" have a wide range. As in past years, special sessions concerning other fields of Functio nal Analysis were organized at the 1981 Conference, but contri butions to these sessions are not included in the present volume. The research contracts of the Department of Mathematics of INCREST with the National Council for Sciences and Technology of Romaliia provided the means for developping the research activity in Functional Analysis; these contracts constitute the generous framework for these meetings. We want also to acknowledge the support of INCREST and the excelent organizing job done by our host - University of Timigoa ra-. Professor Dumitru Gagpar and Professor Mircea Reghig are among those people in Timigoara who contributed in an essential way to the success of the meeting.

Inhalt

The Stone-Weierstrass Problem for C-Algebras.- On the Norm-Closure of the Similarity Orbit of Essentially Nilpotent Operators.- Invariant Subspaces and Functional Representations for the C1. Contractions.- Intertwinings and Hyperinvariant Subspaces.- On Moduli for Invariant Subspaces.- An Extension of Chacon-Ornstein Ergodic Theorem.- Commuting Subnormal Operators Quasisimilar to Multiplication by Coordinate Functions on ODD Spheres.- Some Properties of Masa's in Factors.- Generalized Resolvents of Dual Pairs of Contractions.- Annihilators of Operator Algebras.- On the Derivations with Norm Closed Range in Banach Spaces.- On Boolean Algebras of Projections and Prespectral Operators.- Control Subspaces of Minimal Dimension, and Spectral Multiplicities.- Derivations of C-Algebras which are Invariant under an Automorphism Group. II.- On Commutators in Properly Infinite W*-Algebras.- A Functional Model for the Unitary Dilation of a Positive Definite Map.- The Levinson Algorithm in Linear Prediction.- Geometric Interpretation of the Essential Minimum Modulus.