Uncertainty in bidirectional transformations

In Model-Driven Engineering, models are primary artifact manipulated by means of automated transformations. Recently, a notion of uncertainty has been introduced in models permitting modelers to postpone design decisions in case of lack of information. Interestingly, other forms of model uncertainty are induced by bidirectional transformations. In fact, in certain situations more than one admissible solution is in principle possible, despite most of the current languages generate only one model at time, possibly not the desired one. In this paper, the uncertainty due to the solution multiplicity in bidirectional transformations is discussed. In particular, we propose to represent the models in the solution space as concretizations of an uncertain model because there are cases where the responsibility of identifying the solution must be left to the modeler. The problem is illustrated by a round-tripping scenario realized with the JTL transformation language.