Analysis of Failing Prolog Executions

The result of a Prolog execution can simply be "no", when the programmer is expecting something else. This symptom is typical of Prolog, and especially requires the help of an execution tracer to get clues of what the problem can be. We present a solution which helps programmers to understand how unexpected failures have occurred. We first propose a hierarchy of failing goals. We argue that there is one kind of leaf failures which is interesting to track at the first place. Then we give the algorithm for our leaf failure tracking and two examples illustrating its use. published in Proceedings of Journ'ees Francophones sur la Programmation Logique, Mai 92, Lille y Author's current address: IRISA/INSA, Campus universitaire de Beaulieu, F-35042 Rennes, ducasse@irisa.fr How many Prolog programmers does it take to change a light bulb ? no. 1 Introduction Program analysis, such as type checking and abstract interpretation has many uses in program development and maintenance. The dat..