To agent-based simulation from System Dynamics

Agent-based simulation (ABS) is a recent modeling technique that is being widely used in modeling complex social systems. Forrester's System Dynamics (SD) is another longstanding technique for modeling social systems. Several classical models of systems, such as the Kermack-McKendrick model of epidemiology, the Lotka-Volterra equations for modeling predator-prey relationships, and the Bass model for innovation diffusion are formulated as systems of differential equations and have corresponding System Dynamics representations as difference equations. The ABS and SD modeling approaches take fundamentally different perspectives when modeling a system, which can be characterized as bottom-up (ABS) versus top-down (SD). Yet many systems can be equivalently modeled by either approach. In this paper, we present a formal specification for SD and ABS models, use the specification to derive equivalent ABS representations, and present an example of an SIR epidemic model having SD and ABS counterparts.