Mutation Subsumption as Relative Incorrectness

This paper attempts to link two lines of research that have proceeded independently so far: Mutant subsumption, which is used to identify redundant mutants; and Relative correctness, which is used to define and analyze software faults. We say that a mutant \(M'\) of a program P subsumes a mutant M of P if and only if any test datum that kills M kills \(M'\). On the other hand, we say that a program \(P'\) is more-correct than a program P with respect to a specification R if and only if whenever program P behaves correctly with respect to R on some input datum, so does program \(P'\). We highlight the relationships between these two concepts and consider some potential synergies between these two research directions.