We report here the results obtained thus far along two distinct but complementary and converging lines of research work. The theme is conceptual data base design (specification), and the work has been going on for a number of years, mainly at the University of Stuttgart, in the Federal Republic of Germany, and at the Pontificia Universidade Cat6lica do Rio de Janeiro, in Brasil. We are glad to acknowledge the collaboration of several colleagues and students, particularly H. Biller, J. M. V. de Castilho, A. Horndasch, C. S. dos Santos, R. Studer, U. Schiel, and I. Waiter. Two other co-workers deservey special recognition, since they have shared in writing the report which originated part A of this book - M.A. Casanova and P.A.S. Veloso. The book is intended as a text for graduate courses on information systems and on data bases. The subject is treated formally, since we do believe that formality leads to precision, a quality that one misses in the still prevailing ad-hoc techniques. The theoretical background is covered, although in a condensed fashion, referring the reader to the appropriate literature for more details.weiterlesen