This book contains the papers presented at the international research sympo sium "Solid Modeling by Computers: From Theory to Applications," held at the General Motors Research Laboratories on September 25-27, 1983. This was the 28th syposium in aseries which the Research Laboratories began sponsor ing in 1957. Each symposium has focused on a topic that is both under active study at the Research Laboratories and is also of interest to the larger technical community. Solid modeling is still a very young research area, young even when com pared with other computer-related research fields. Ten years ago, few people recognized the importance of being able to create complete and unambiguous computer models of mechanical parts. Today there is wide recognition that computer representations of solids are aprerequisite for the automation of many engineering analyses and manufacturing applications. In September 1983, the time was ripe for a symposium on this subject. Re search had already demonstrated the efficacy of solid modeling as a tool in computer automated design and manufacturing, and there were significant re suIts wh ich could be presented at the symposium. Yet the field was still young enough that we could bring together theorists in solid modeling and practition ers applying solid modeling to other research areas in a group sm all enough to allow a stimulating exchange of ideas.