Center for Analysis and Design of Intelligent Agents

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E-217-PROG-2010-1: Simulation 2 Thorisson Lecture Notes

Modularity	A modular system is one with well-defined interfaces between components. A house made of LEGO bricks is modular because the elements it is made of have a well defined studs-tubes that can be interfaced.
Input/Output	A system that requires initialization or data to produce its effects requires Input. A system's change of the input state or its production of new data is its Output.
Nonlinearity	A nonlinear system is a system whose output is not proportional to its input.
Emergence	A phenomenon is called emergent if the interaction of many components at one level of description gives rise to a new phenomenon at a higher level of description. Emergence cartoon
Second-order emergence	When an emergent phenomenon, like a society, gives rise to other emergent phenomena within it, e.g. a police force and government.
Micro-level	In psychology: the cognitive function. (In sociology: the individual.)
Macro-level	In psychology: the individual. (In sociology: the society.)

Creating a model	The model is the “story” – equivalent to a scientific theory (from small to large).
Implementing the model	Choosing platform, programming language, etc., and writing the program.
Debugging	Getting rid of bugs.
Grounding	Making sure the simulation relates to reality.

Determine the scope	What set of questions would we want to be able to answer with our simulation? What are the most extreme conditions that the system should be able to take? What is a typical set of questions we will study?
Simplification
Define parameters	Decide which variables should be independent and dependent; deciding on how to represent these in variables in the selected programming language.
Define processes	What are the operations we want to manipulate the parameters? What are their inputs and outputs?
Define interactions between processes	How can the processes defined interact with each other?
Decide analysis methods	How do we want to analyze the results? What are the main variables to watch?

Selecting a programming language
Programming
Incremental development

Cellular Automata	A.k.a. CA Grid-based computing system where each cell can have two or more states and looks at its neighbors to determine its next state. CA
Agent-oriented	A.k.a. Multi-agent simluations. Use the concept of semi-autonomous programs that interact with each other. Compared to e.g. the cells in CAs each agent is typically very complex (think of it as a full computer program executable).

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