Visualizing the Execution of Prolog Programs

Visualizing the Execution of Prolog Programs
Marc Eisenstadt, Mike Brayshaw - The Open University
CHI '88 Technical Video Program
Abstract
This videotape illustrates a graphical Prolog execution model which serves as the basis for Open University teaching material as well as an advanced graphical user interface for expert Prolog programmers. Our aim has been to reconcile a global view of Prolog program execution with the 'truth' about finegrained execution details. The cornerstone of our graphical representation is the 'AORTA' diagram, an And/OR Tree, augmented to include invocation history 'status boxes' at each node. This augmentation makes it possible to present a graphical view of Prolog execution which is very compact, yet which contains complete details of unification and control history, including multiple (backtracking) invocations and extra-logical control features such as the 'cut'. The video contains excerpts from Open University course materials based on AORTA diagram notation. In particular, it illustrates the inner workings of the 'Prolog interpreter list-processing. Only the finegrained (close-up) view is illustrated in the video.
WEB:: www.cs.umd.edu/...
Published as Issue 58-59 of ACM SIGGRAPH Video Review.
Video Chair: James Hollan (MCC)
Location: Washington, DC, USA