  We consider the problem of defining a strategy consisting of a set of
facilities taking into account also the location where they have to be assigned
and the time in which they have to be activated. The facilities are evaluated
with respect to a set of criteria. The plan has to be devised respecting some
constraints related to different aspects of the problem such as precedence
restrictions due to the nature of the facilities. Among the constraints, there
are some related to the available budget. We consider also the uncertainty
related to the performances of the facilities with respect to considered
criteria, and plurality of stakeholders participating to the decision. The
considered problem can be seen as the combination of some prototypical
operations research problems: knapsack problem, location problem and project
scheduling. Indeed, the basic brick of our model is a variable $x_{ilt}$ which
takes value 1 if facility $i$ is activated in location $l$ at time $t$, and $0$
otherwise. Due to the conjoint consideration of a location and a time in the
decision variables, what we propose can be seen as a general space-time model
for operations research problems. We discuss how such a model permits to handle
complex problems using several methodologies including multiple attribute value
theory and multiobjective optimization. With respect to the latter point,
without any loss of the generality, we consider the compromise programming and
an interactive methodology based on the Dominance-based Rough Set Approach. We
illustrate the application of our model with a simple didactic example.
