Simulation is now recognized as powerful tool in project, analyses and operation of produtive systems. Although the recent advances in simulation languages, graphical interfaces and in generating applications, simulation is still an expensive and not so efficient technique. In this text we dicuss some reasons for this in the context of not well strutured problems, asit is the case of production planning and control. It is also dicussed the necessity of developing the conceptual modeling of the real system, not only as a separated step in the simulation process, but in a progressive and dynamic way, during the project's life cycle as an interface between the real system and simulation.
Simulation; Modelling; VIM - Visual interactive Modelling
