The evolution of programs: A system for automatic program modification

A programmer spends more time modifying already existing programs than constructing original ones. An attempt is made to formulate techniques of program modification, whereby a program that achieves one result can be transformed into a new program that uses the same piinciples to achieve a different goal. For example, a piogram that uses the binary search paradigm to divide two numbers may be modified to calculate the square-root of a number in a similar manner. Program debugging is considered as a special case of modification- if a piogram computes wrong results, it must be modified to achieve the intended lesults The application of abstiact piogiam schemata to concrete problems is also viewed from the peispeclive of modification techniques. We. have embedded this approach in a running implementation; our methods ate illustrated with several examples that have been performed by it.