Three Forms of Mutant Subsumption: Basic, Strict and Broad.

Mutant subsumption is the property of a mutant to be more stubborn than another, i.e. to be harder to distinguish from the base program. The traditional definition of mutant subsumption distinguishes between three forms of subsumption, namely: true subsumption, static subsumption, and dynamic subsumption. Also, the traditional definition of mutant subsumption appears to assume that programs and their mutants converge for all test data, but in practice this is not the case: executions may lead to infinite loops or attempt illegal operations of all kinds. In this paper we revisit the definition of mutant subsumption by taking into consideration the possibility that executions may diverge, and we propose an orthogonal classification of subsumption.