(Requirement) evolution requirements for adaptive systems

It is often the case that stakeholders want to strengthen/weaken or otherwise change their requirements for a system-to-be when certain conditions apply at runtime. For example, stakeholders may decide that if requirement R is violated more than N times in a week, it should be relaxed to a less demanding one R-. Such evolution requirements play an important role in the lifetime of a software system in that they define possible changes to requirements, along with the conditions under which these changes apply. In this paper we focus on this family of requirements, how to model them and how to operationalize them at runtime. In addition, we evaluate our proposal with a case study adopted from the literature.