The concept of intelligent CAD systems to assist a designer in automating the design process has been discussed for years. It has been recognized that knowledge engineering techniques and the study of design theory can provide certain solutions to this approach. A major issue in developing intelligent CAD systems for geometric modeling is the integration of the design geometry with the representation of the design constraints. Current commercial computer aided design (CAD) systems are used primarily for recording the results of the design process. Using conventional CAD systems, a design engineer either must create the geometry of the design object with precise coordinates and dimensions, or start his design from an existing geometry of a previous design. It is difficult to propagate a dimensional change throughout an entire model -- especially solid models. This rigidity imposed by conventional CAD systems discourages a designer from exploring different approaches in creating a novel product. / Ph. D.