Sugarscape
Encyclopedia
Sugarscape is a model artificially intelligent
agent-based social simulation
following some or all rules presented by Joshua M. Epstein
& Robert Axtell
in their book Growing Artificial Societies.
where economist Thomas Schelling
presented his paper titled Models of Segregation. 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 Conway
's agent-based simulation "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". Since then, the name "Sugarscape" has been used for agent-based models using rules similar to those defined by Epstein & Axtell.
(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 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.
Exact simulation of the original rules provided by J. Epstein & R. Axtell in their book can be problematic and it is not always possible to recreate the same results as those presented in Growing Artificial Societies.
software.
software suitable for agent-based social simulation
. The Sugarscape model remains part of the built-in library of models distributed with Ascape.
and later in Java by Mark A. O'Neill
. It can be easily used by other researchers as a test-bed, where can they lay out their theory in terms of initial and subsequent states of the Sugarscape. The patterns resulting from the execution of the simulation can be used to confirm or revise their claims. For example, a thesis about links between population concentrations and soil fertility could be explored by setting varying levels of fertility and noting the corresponding populations that the Sugarscape is able to support. The web version can be freely used to test parameter variations for different scenarios or downloaded as a whole project and the source files modified at will.
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)." The model is equipped with rich documentation including instructions for successful replication of the original Sugarscape rules.
, 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 millions.
's MASON
project, available under the Academic Free License
, also includes an implementation of Sugarscape.
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...
agent-based social simulation
Social simulation
Social simulation is a research field that applies computational methods to study issues in the social sciences. The issues explored include problems in sociology, political science, economics, anthropology, geography, archaeology and linguistics ....
following some or all rules presented by Joshua M. Epstein
Joshua M. Epstein
Joshua M. Epstein is Professor of Emergency Medicine at Johns Hopkins University, and a member of the External Faculty of the Santa Fe Institute.- Early life and Education:Epstein was born in New York City and grew up in Amherst....
& Robert Axtell
Robert Axtell
- References :...
in their book Growing Artificial Societies.
Origin
Fundaments of Sugarscape models can be traced back to the University of MarylandUniversity of Maryland, College Park
The University of Maryland, College Park is a top-ranked public research university located in the city of College Park in Prince George's County, Maryland, just outside Washington, D.C...
where economist Thomas Schelling
Thomas Schelling
Thomas Crombie Schelling is an American economist and professor of foreign affairs, national security, nuclear strategy, and arms control at the School of Public Policy at University of Maryland, College Park. He is also co-faculty at the New England Complex Systems Institute...
presented his paper titled Models of Segregation. Written in 1969, Schelling and the rest of the social environment
Social environment
The social environment of an individual, also called social context or milieu, is the culture that s/he was educated or lives in, and the people and institutions with whom the person interacts....
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 Conway
John Horton Conway
John Horton Conway is a prolific mathematician active in the theory of finite groups, knot theory, number theory, combinatorial game theory and coding theory...
's agent-based simulation "Game of Life
Conway's Game of Life
The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970....
" was enhanced and applied to Schelling's original idea by Joshua M. Epstein
Joshua M. Epstein
Joshua M. Epstein is Professor of Emergency Medicine at Johns Hopkins University, and a member of the External Faculty of the Santa Fe Institute.- Early life and Education:Epstein was born in New York City and grew up in Amherst....
and Robert Axtell
Robert Axtell
- References :...
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". 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 agentsIntelligent agent
In artificial intelligence, an intelligent agent is an autonomous entity which observes through sensors and acts upon an environment using actuators and directs its activity towards achieving goals . Intelligent agents may also learn or use knowledge to achieve their goals...
(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 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.
Exact simulation of the original rules provided by J. Epstein & R. Axtell in their book can be problematic 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 sourceOpen source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
software.
Ascape
An original implementation was developed in Ascape, JavaJava (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
software suitable for agent-based social simulation
Agent-based social simulation
Agent-based social simulation consists in social simulations that are based on Agent-based modeling, and implemented using artificial agent technologies....
. The Sugarscape model remains part of the built-in library of models distributed with Ascape.
Sugarscape.sourceforge.net
Sugarscape.sourceforge.net is a complex and developed implementation of the original Sugarscape model, originally written in Object PascalObject Pascal
Object Pascal refers to a branch of object-oriented derivatives of Pascal, mostly known as the primary programming language of Embarcadero Delphi.-Early history at Apple:...
and later in Java by Mark A. O'Neill
Mark A. O'Neill
Mark A. O'Neill is an English biologist and computer scientist with interests in artificial intelligence, systems biology, complex systems and image analysis...
. It can be easily used by other researchers as a test-bed, where can they lay out their theory in terms of initial and subsequent states of the Sugarscape. The patterns resulting from the execution of the simulation can be used to confirm or revise their claims. For example, a thesis about links between population concentrations and soil fertility could be explored by setting varying levels of fertility and noting the corresponding populations that the Sugarscape is able to support. The web version can be freely used to test parameter variations for different scenarios or downloaded as a whole project and the source files modified at will.
NetLogo
NetLogoNetLogo
NetLogo is a multi-agent programming language and integrated modeling environment.-About:NetLogo was designed in the spirit of the Logo programming language to be "low threshold and no ceiling," that is to enable easy entry by novices and yet meet the needs of high powered users. The 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)." The model is equipped with rich documentation including instructions for successful replication of the original Sugarscape rules.
SugarScape on steroids
Due to the emergent nature of Agent-based models (ABMs), it is critical that the population sizes in the simulations match the population sizes of the dynamic systems being modelled. 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 clusters has been limited by available bandwidth. As computing power increases with Moore's lawMoore's Law
Moore's law describes a long-term trend in the history of computing hardware: the number of transistors that can be placed inexpensively on an integrated circuit doubles approximately every two years....
, 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
Michigan Technological University
Michigan Technological University is a public research university located in Houghton, Michigan, United States. Its main campus sits on on a bluff overlooking Portage Lake...
used a Sugarscape model to demonstrate the power of Graphics processing unit
Graphics processing unit
A graphics processing unit or GPU is a specialized circuit designed to rapidly manipulate and alter memory in such a way so as to accelerate the building of images in a frame buffer intended for output to a display...
s (GPU) in ABM simulations with over 50 updates per second with agent populations exceeding 2 millions.
MASON
GMUGeorge Mason University
George Mason University is a public university based in unincorporated Fairfax County, Virginia, United States, south of and adjacent to the city of Fairfax. Additional campuses are located nearby in Arlington County, Prince William County, and Loudoun County...
's MASON
MASON (Java)
MASON is an multi-agent simulation environment developed in Java at George Mason University's Evolutionary Computation Laboratory in conjunction with the GMU Center for Social Complexity. First released in 2003, the environment continues to be maintained and kept up to date...
project, available under the Academic Free License
Academic Free License
The Academic Free License is a permissive free software license written in 2002 by Lawrence E. Rosen, the general counsel of the Open Source Initiative ....
, also includes an implementation of Sugarscape.