Seven layers of knowledge representation and reasoning in supportof software development

The authors' experience in the Programmer's Apprentice project in applying knowledge representation and automated reasoning to support software development is summarized. A system, called Cake, is described that comprises seven layers of knowledge representation and reasoning facilities: truth maintenance, Boolean constraint propagation, equality, types, algebra, frames, and Plan Calculus. Sessions with two experimental software development tools implemented using Cake, the Requirements Apprentice and the Debugging Assistant, are also included