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{{For|the youth website|Sugarscape.com}}
'''Sugarscape''' is a model for [[Artificial intelligence|artificially intelligent]] [[Agent-based model|agent-based]] [[social simulation]] following some or all rules presented by [[Joshua M. Epstein]] & [[Robert Axtell]] in their book ''Growing Artificial Societies''.<ref name="GAS">{{cite book
|first1=Joshua M.
|last1=Epstein
|authorlink1=Joshua M. Epstein
|first2=Robert
|last2=Axtell
|authorlink2=Robert Axtell
|title=Growing artificial societies: social science from the bottom up
|publisher=Brookings Institution Press
|date=October 11, 1996
|pages=[https://archive.org/details/growingartificia00epst/page/224 224]
|isbn=978-0-262-55025-3
|url-access=registration
|url=https://archive.org/details/growingartificia00epst/page/224
}}</ref>

==Origin==
Fundaments of Sugarscape models can be traced back to the [[University of Maryland, College Park|University of Maryland]] where economist [[Thomas Schelling]] presented his paper titled ''[[Thomas Schelling#Models of segregation|Models of Segregation]]''.<ref name="Sourceforge1">{{cite web
|url=http://sugarscape.sourceforge.net/ |title=Sugarscape - Growing Agent-based Artificial Societies |publisher=[[Sourceforge]] |accessdate=7 November 2010}}</ref> Written in 1969, Schelling and the rest of the [[social environment]] modelling fraternity had their options limited by a lack of adequate computing power and an applicable programming mechanism to fully develop the potential of their model.

[[John Horton Conway|John Conway]]'s agent-based simulation "[[Conway's Game of Life|Game of Life]]" was enhanced and applied to Schelling's original idea by [[Joshua M. Epstein]] and [[Robert Axtell]] in their book ''Growing Artificial Societies''. To demonstrate their findings on the field of agent-based simulation, a model was created and distributed with their book on CD-ROM. The concept of this model has come to be known as "the Sugarscape model".<ref name="GAS" /> Since then, the name "Sugarscape" has been used for agent-based models using rules similar to those defined by Epstein & Axtell.

==Principles==
All Sugarscape models include the [[Intelligent agent|agents]] (inhabitants), the environment (a two-dimensional grid) and the rules governing the interaction of the agents with each other and the environment.

The original model presented by J. Epstein & R. Axtell (considered as the [[Social simulation#History and development|first large scale agent model]]) is based on a 51x51 cell grid, where every cell can contain different amounts of sugar (or spice). In every step agents look around, find the closest cell filled with sugar, move and metabolize. They can leave pollution, die, reproduce, inherit sources, transfer information, trade or borrow sugar, generate immunity or transmit diseases - depending on the specific scenario and variables defined at the set-up of the model.

Sugar in simulation could be seen as a metaphor for resources in an artificial world through which the examiner can study the effects of social dynamics such as evolution, marital status and inheritance on populations.<ref>{{cite journal
|url=http://www.allbusiness.com/science-technology/experimentation-research/13434481-1.html
|title=Agents at Work
|date=1 June 2003
|journal=CIO Insight
|volume=1
|issue=27
|page=43
|accessdate=November 11, 2010
|issn=1535-0096
}}(Retrieved from [[ProQuest|ABI/Inform]] Document ID: 347271391)</ref>

Exact simulation of the original rules provided by J. Epstein & R. Axtell in their book can be problematic<ref name="tricky">{{cite web
|url=http://www2.le.ac.uk/departments/interdisciplinary-science/research/replicating-sugarscape
|title=Replicating Sugarscape — University of Leicester
|accessdate=18 January 2011
|archive-url=https://web.archive.org/web/20120619172718/http://www2.le.ac.uk/departments/interdisciplinary-science/research/replicating-sugarscape
|archive-date=2012-06-19
}}</ref> and it is not always possible to recreate the same results as those presented in ''Growing Artificial Societies''.

==Model implementations==
The Sugarscape model has had several implementations, some of which are available as [[Open-source software|open source]] software.

===Ascape===
An original implementation was developed in [[Ascape]], [[Java (programming language)|Java]] software suitable for [[agent-based social simulation]]. The Sugarscape model remains part of the built-in library of models distributed with Ascape.<ref>{{cite web
|url=http://ascape.sourceforge.net/manual/Section1.html
|title=The Ascape Model Developer's Manual
|publisher=[[Sourceforge]]
|accessdate=9 November 2010
}}</ref>

===NetLogo===
[[NetLogo]] has been used to build Sugarscape models. Three Sugarscape scenarios are included in the NetLogo Models Library: "Immediate Growback", "Constant Growback" and "Wealth Distribution". Besides these three scenarios lies Iain Weaver's Sugarscape NetLogo model, which is part of the User Community Models Library. "It builds on Owen Densmore's NetLogo community model to encompass all rules discussed in ''Growing Artificial Societies'' with the exception of the combat rule (although trivial to include, it adds little value to the model)."<ref>{{cite web
|url=http://ccl.northwestern.edu/netlogo/models/community/Sugarscape
|title=NetLogo User Community Models: Sugarscape
|accessdate=9 November 2010
}}</ref> The model is equipped with rich documentation<ref>{{cite web
|url=http://www2.le.ac.uk/departments/interdisciplinary-science/research/the-sugarscape
|title=The Sugarscape
|publisher=[[University of Leicester]]
|accessdate=19 January 2011
|archive-url=https://web.archive.org/web/20171002025754/http://www2.le.ac.uk/departments/interdisciplinary-science/research/the-sugarscape
|archive-date=2017-10-02
}}</ref> including instructions for successful replication of the original Sugarscape rules.<ref name="tricky"/>

===SugarScape on steroids===

Due to the emergent nature of [[agent-based model]]s (ABMs), it is critical that the population sizes in the simulations match the population sizes of the dynamic systems being modelled.<ref>{{cite journal
|last1=Gilbert
|first1=Nigel
|last2=Bankes
|first2=Steven
|year=2002
|title=Platforms and Methods for Agent-Based Modelling
|journal=Proceedings of the National Academy of Sciences
|url=http://www.pnas.org/cgi/reprint/99/suppl_3/7197.pdf
|volume=99
|issue=3
|pages=7197–7198
|doi=10.1073/pnas.072079499 |pmc=128584
|pmid=12011398
}}</ref> However, the performance of contemporary agent simulation frameworks has been inadequate to handle such large population sizes and parallel computing frameworks designed to run on [[computing cluster]]s has been limited by available bandwidth. As computing power increases with [[Moore's law]], the size and complexity of simulation frameworks can be expected to increase. The team of R. M. D’Souza, M. Lysenko and K Rahmani from [[Michigan Technological University]] used a Sugarscape model to demonstrate the power of [[Graphics processing unit]]s (GPU) in ABM simulations with over 50 updates per second with agent populations exceeding 2 million.<ref>{{cite journal
|title=SugarScape on steroids: simulating over a million agents at interactive rates
|first1=Roshan M.
|last1=D'Souza
|first2=Mikola
|last2=Lysenko
|first3=Keyvan
|last3=Rahmani
|url=http://www.me.mtu.edu/~rmdsouza/Papers/2007/SugarScape_GPU.pdf
|journal=Proceedings of Agent2007 Conference
|location=Chicago, Il
|year=2007}}(See also: [http://www.me.mtu.edu/~rmdsouza/Papers/2007/SugarScape_Slides.pdf presentation slides])</ref>

===Mathematica===
Another implementation can be found written in [[Mathematica]].<ref>{{cite web
|url=http://demonstrations.wolfram.com/SugarscapeAgentBasedModeling/
|title=Sugarscape: Agent-Based Modeling<!--sic--> - Wolfram Demonstrations Project
|publisher=[[Wolfram Research|Wolfram]]
|accessdate=18 January 2011}}</ref>

===MASON===
[[George Mason University|GMU]]'s [[Mason (Java)|MASON]] project, available under the [[Academic Free License]], also includes an implementation of Sugarscape.<ref>{{cite journal
|last1=Bigbee
|first1=Anthony
|first2=Claudio
|last2=Cioffi-Revilla
|first3=Sean
|last3=Luke
|year=2007
|title=Replication of Sugarscape Using MASON
|journal=Agent-Based Approaches in Economic and Social Complex Systems IV: Post-Proceedings of the AESCS International Workshop 2005
|editor1-first=T.
|editor1-last=Terano
|editor2-first=H.
|editor2-last=Kita
|editor3-first=H.
|editor3-last=Deguchi
|editor4-first=K.
|display-editors = 3 |editor4-last=Kijima
|publisher=Springer
|location=Tokyo
|url=http://cs.gmu.edu/~eclab/projects/mason/publications/replication2007.pdf
}}</ref>

==References==
{{reflist|2}}

==External links==
* [http://ccl.northwestern.edu/netlogo/models/ NetLogo Models Library]
** [http://ccl.northwestern.edu/netlogo/models/Sugarscape1ImmediateGrowback NetLogo: Immediate Growback]
** [http://ccl.northwestern.edu/netlogo/models/Sugarscape2ConstantGrowback NetLogo: Constant Growback]
** [http://ccl.northwestern.edu/netlogo/models/Sugarscape3WealthDistribution NetLogo: Wealth Distribution]
** [http://ccl.northwestern.edu/netlogo/models/community/index.cgi NetLogo: Community Models Library]
*** [http://ccl.northwestern.edu/netlogo/models/community/Sugarscape NetLogo Community Models: Sugarscape]
* [http://demonstrations.wolfram.com/SugarscapeAgentBasedModeling/ Sugarscape in Mathematica]
* [https://web.archive.org/web/20110812192838/http://web.mac.com/tony.bigbee/mason_sugarscape/MASON_Sugarscape.html Sugarscape in MASON]

{{DEFAULTSORT:Sugarscape}}
[[Category:Cellular automaton rules]]
[[Category:Self-organization]]
[[Category:Artificial life]]
[[Category:Free software]]