The Role of the Environment in Simulating Multi-Agent Systems Alexander Helleboogh, Tom Holvoet and Danny Weyns October 3, 2007 1 Scope Simulation is important to support the development of multi-agent systems (MAS). Simulation offers a safe and cost-effective way for studying, evaluating and configuring the behavior of a MAS in a simulated environment before the MAS is deployed in the real world. Such simulations are often referred to as software-in-the-loop simulations [2]: the software of the real MAS application is embedded in the simulation. The MAS is not substituted by a model, but the MAS software itself is part of the simulation loop. 2 The Concrete Subject In this chapter, we focus on the role of the environment in the context of software-in-the-loop simulations of MAS. In the real world, a MAS is situated in a particular environment. The envi- ronment is the part of the external world with which the MAS software interacts, and in which the effects of the MAS will be observed [5]. The task of the MAS is to ensure that particular functionalities are achieved in the environment. The environment of a MAS is typically dynamic. In a dynamic environment the operating conditions of a MAS are continuously changing. For example, in a manufacturing environment new materials and product orders may arrive; other machines, vehicles and/or humans are operating, etc. It is essential that a MAS takes into account the dynamic environment in which it is situated, as such changing operating conditions can have a significant impact on its operation. Consequently, when relying on simulation for studying, evaluating and/or con- figuring the behavior of a MAS, it is paramount to deal with the dynamic nature of the environment. To support dynamic environments in software-in-the-loop simulations of MAS, we put forward (1) a modeling framework that offers support for cap- turing dynamic environments in the simulation model, and (2) an architecture that describes how support for dynamic environments can be integrated in a simulation platform. 1