The Layered Architecture of a System for Reasoning about Programs

Cake is a hybrid system which provides reasoning facilities for the Programmer's Apprentice. This paper describes the architecture of Cake, which is divided into eight layers, each with associated representations and reasoning procedures. The operation of Cake is illustrated by a complete trace of the solution of an example reasoning problem. We also argue that a hybrid system in general is characterized by the use of multiple representations in the sense of multiple data abstractions, which does not necessarily imply distinct implementation data structures.