NetLogo User Community Models

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Download If clicking does not initiate a download, try right clicking or control clicking and choosing "Save" or "Download".(The run link is disabled for this model because it was made in a version prior to NetLogo 6.0, which NetLogo Web requires.)

VERSION

For use with NetLogo 4.0.4

WHAT IS IT?

A version of SugarScape, as presented in "Growing Artificial Societies" by Epstein and Axtell. It builds on Owen Densmore's NetLogo community model to encompass all rules discussed in GAS with the exception of the combat rule (although trivial to include, it adds little value to the model).

HOW IT WORKS

Patches represent a toroidal world with "sugar" (representing wealth) deposited in two roughly circular regons or "hills" of increasing sugar density. Agents and patches follow a number of rules designed to deomonstrate various properties that emerge from this simple artificial society.

Agent rules
M: Enables agents to move about the Sugarscape, eat sugar and metabolise
P: Causes agents to leave pollution where they eat and metabolise
R: Replaces dead agents with a new randomly generated agent
S: Enables sexual reproduction between agents
I: Enables accumulated wealth to be passed down to children on an agents death
K: Enables transmission of cultural information
T: Enables agents to engage in trade between two resources
L: Enables agents to borrow sugar for reproduction
E: Enables agents to generate an immune response to, and transmit disease

Patch rules
G: Causes sugar to grow back at each patch
D: Causes accumulated pollution to diffuse to adjacent patches
Seasons: Half of the Sugarscape regrows at a much lower rate, and periodically switches.

HOW TO USE IT

The chooser labelled "Presets" offers a variety of settings to explore the scope of the Sugarscape. To set model parameters to the presets, click "Setup Preset".

THINGS TO TRY

The Sugarscape can be home to a colourful variety of emergant structure and behavior. How to use the interface, and information on the different presets, and effects that can be seen are discussed more in a document which can be found here:

http://www2.le.ac.uk/departments/interdisciplinary-science/research/the-sugarscape

EXTENDING THE MODEL

This version of Sugarscape has been very successful in achieving the same results as those presented in GAS. However, several observations have not been successfully recreated, and it is unclear how GAS implimented some combinations of rules, such as L in the two resources landscape.

Discrepancies are discussed more thoroughly here:

http://www2.le.ac.uk/departments/interdisciplinary-science/research/replicating-sugarscape

CREDITS AND REFERENCES

Owen Densmore, Sugarscape (2003 NetLogo community model)
JM Epstein and R Aktell, Growing Artificial Societies (MIT Press, 1996)