ConceptBase - A Deductive Object Base Manager M. Jarke, St. Eherer, R. Gallersdoerfer, M. Jeusfeld, M. Staudt Deductive object bases attempt to combine the advantages of deductive relational databases with those of object-oriented models. We review modeling and optimization issues encountered during the development of ConceptBase, a prototype deductive object base supporting the Telos data model. We also report on a number of application experiences in the field of meta data management.