Formal modeling for product families engineering

In this paper we propose a behavioural model, namely the Generalized Extended Modal Transition Systems, as a basis for the formalization of different notions of variability usually present in product families definitions. In particular, a GEMTS is able to define a family of products by telling at any state of the system whether some (and how many) transitions are optional or mandatory for any derived products of the family. The proposed model is compared with previous proposals also based on Labeled Transition Systems, showing its higher generality, but also pointing out weaknesses that still need to be addressed with more expressive models. Hints on the solution of such weaknesses are given by the use of constraints expressed as temporal logic formulae.