A System to Improve incorrect Programs

Summery : This paper presents e system (PHENARETE) which understands and improves incompletely defined LISP programs, such as those written by students beginning t,o program in LISP. This system takes, as input, the program without any additional information. In order to understand the program, the system mete-evaluates it, using a library of praqmatic rules, describing the construction and correction of general program constructs, end a set of specialists, describing the syntax end semantics of the standard LISP functions. The system can use its understanding of the program to detect errors in it, to eliminate them and, eventually, to justify its proposed modifications. This paper gives a brief survey of the working of the system, emphasizing some commented examples.