Program Repair by Stepwise Correctness Enhancement
This work addresses program testing and repair for software developers, but it is incremental as it builds on existing concepts of relative correctness.
The paper tackles the problem of program repair by proposing to test new programs for relative correctness over old ones instead of absolute correctness, and demonstrates this approach with a small program where faults are removed stepwise until correctness is achieved.
Relative correctness is the property of a program to be more-correct than another with respect to a given specification. Whereas the traditional definition of (absolute) correctness divides candidate program into two classes (correct, and incorrect), relative correctness arranges candidate programs on the richer structure of a partial ordering. In other venues we discuss the impact of relative correctness on program derivation, and on program verification. In this paper, we discuss the impact of relative correctness on program testing; specifically, we argue that when we remove a fault from a program, we ought to test the new program for relative correctness over the old program, rather than for absolute correctness. We present analytical arguments to support our position, as well as an empirical argument in the form of a small program whose faults are removed in a stepwise manner as its relative correctness rises with each fault removal until we obtain a correct program.