Constraint Definition System: A computer-algebra based approach to solving geometric-constraint problems

During the computer-aided design of assemblies, or of single objects composed of primitive elements, the positions of their constituent parts must be determined. These parts can be positioned absolutely in terms of some coordinate system, or relatively in terms of the relationships or constraints that implicitly exist between their constituents. Despite having many advantages, the latter approach presents computational problems which have resulted in its limited acceptance. The paper describes a system which uses techniques from computer algebra to avoid these problems, and discusses its advantages and disadvantages.