The Marktoberdorf Summer Schools on Informatics were started in 1970, with the intention to convene every second or third year a group of top researchers in computing, devoted to preach their most recent results to an elite of advanced students - young and most promising people - and prepared to stand their questions, criticism and suggestions. The themes of these Advanced Study In stitutes under the sponsorship of the NATO Scientific Affairs Division varied slightly over the years, oscillating more or less around Programming Methodo logy, as the following list shows: 1970 Data Structures and Computer Systems 1971 Program Structures and Fundamental Concepts of Programming 1973 Structured Programming and Programmed Structures 1975 Language Hierarchies and Interfaces 1978 Program Construction 1981 Theoretical Foundations of Programming Methodology 1984 Control Flow and Data Flow: Concepts of Distributed Programming 1986 Logic of Programming and Calculi of Discrete Design 1988 Constructive Methods in Computing Science 1989 Logic, Algebra, and Computation Logic, Algebra, and Computation is the theme of the summer school to which this volume is devoted. It is the tenth in succession, but it is also the first in a new series (the blue series) that is intended to alternate in future with the traditional (the red series) arrangement; in fact the tenth summer school in the red series with the title Programming and Mathematical Method , held in 1990, was the subject of celebrating both its serial number and the twenty years of Marktoberdorf Summer Schools altogether.