Agent-Based Model

Agent-based modelling (ABM) is the modelling of phenomena as dynamical systems of interacting agents. An '''agent-based model''' is a specific individual based computational model for the computer simulation of [[Complex_System|complex systems]]. ABM can be used as abbreviation for both, Agent-Based Modelling or Agent-Based Model.

An agent-based model is a computational model in which every participant in a system or process is modelled indivdually. A system is modeled as a collection of autonomous decision-making entities called [[Agent|agents]]. In agent-based modeling the word 'model' often means to specify 'the rules of the game': to specify exactly what kind of participants exist (the agents and their states) and how they interact (the rules). As Bonabeau says in his paper about [http://www.pnas.org/cgi/content/full/99/suppl_3/7280 agent-based modeling] "at the simplest level, an agent-based model consists of a system of agents and the relationships between them". ABMs are the equivalent to games in [http://en.wikipedia.org/wiki/Game_theory game theory]. A strategic game in game theory consists of a set of players, a set of moves (or strategies) available to those players, and a specification of payoffs for each combination of strategies. An ABM consists of a set of (simplified) agents, a set of possible basic behaviors or  elementary interactions, and a set of rules which specifies the evolution or development of the system.

Contrary to general [[Multi-Agent System|multi agent systems]], an ABM describes the interactions among individual [[Agent|agents]] and their environment in a specific situation which leads to particular organizational patterns and [[Emergence|emergent properties]]. Model in 'agent-based model' is used in the sense of an abstract representation of a concrete system from a particular viewpoint. ABMs can be used to explain collective human behavior in the social sciences, to understand [[Complex System|complex systems]], and they enable the user to run large scale virtual experiments without altering the corresponding real [[System|system]].