Models, Representations and Comparisons in Computer Simulations

In this paper we revisit fundamentals of modeling and discuss the notions of models, representations, validation and verification, and many other basic concepts. We argue that the key notions about model and simulation quality, i.e. of what constitites valid simulations, can be understood and also classified using the simple concept of comparison. To arrive at this conclusion, we first discuss our basic understanding of modeling and that of the simulation process. Throughout the paper we will discuss issues related to computer simulation in full generality, but occasionally we will also refer to particular points concerning our own domain of work, agent-based simulations.