More than forty years have passed since the early attempts to model projects. A large domain of theoretical developments has grown producing a high number of analytical and numerical results, but it seems that the main model is still the same: the concept of project network. This concept has come to represent the two major features underlying the notion of a project: the sequential and the competitive nature of its components, the project's activities. Actually, the sequential property defines the structure of the project and the competitive nature stems from the use of common resources...