Research Sites and Groups

Last Updated: 9 March 2024

Site Developed By:

Leigh Tesfatsion

Professor Emerita of Economics

Courtesy Research Professor of

    Electrical & Computer Engineering

Heady Hall 260

Iowa State University

Ames, Iowa 50011-1054

https://faculty.sites.iastate.edu/tesfatsi

tesfatsi AT iastate.edu

Agent-Based Computational Economics (ACE) Website:

https://www2.econ.iastate.edu/tesfatsi/ace.htm

• Support for New Economic Thinking
• Agent-Based Computational Economics (ACE)
• Economic and Social Network Formation
• Evolution
• Complex Adaptive Systems (CAS)
• Artificial Life and Artificial Intelligence
• Learning and Human Cognition
• Evolutionary Computation
• Demos, Software, and Software Development
• Miscellaneous Sites of Possible Interest

Site Disclaimer:

The number of ACE/ABM/CAS research sites and groups has now grown so large that it is no longer possible to provide a comprehensive up-to-date listing. Below are annotated links to ACE/ABM/CAS sites and groups active during earlier years that visitors might still find useful and/or of historical interest even if the links are now broken.

Support for New Economic Thinking

• The European Association for Evolutionary Political Economy (EAEPE) is an active scholarly association in the area of institutional and evolutionary economics broadly conceived. The Association has developed into a pluralistic forum with room for a variety of approaches. One of the research areas supported by the EAEPE at its annual conferences through designated sessions is Evolutionary Economic Simulations (EES).

• From Human-Subject Experiments to Computational-Agent Experiments (and Everything in Between)

• The Institute for New Economic Thinking (INET) was created to broaden and accelerate the development of new economic thinking that can lead to solutions for the great challenges of the 21st century. The havoc wrought by our recent global financial crisis has vividly demonstrated the deficiencies in our outdated current economic theories, and shown the need for new economic thinking - right now. INET is supporting this fundamental shift in economic thinking through research funding, community building, and spreading the word about the need for change. We already are a global community of thousands of new economic thinkers, ranging from Nobel Prize winning economists to teachers and students who have emerged out from the shadows of prevailing economic thought, attracted by the promise of a free and open economic discourse.

• The Journal of Evolutionary Economics, founded in 1991, has been the affiliated journal of the ISS since 1993.

• Under the direction of Roger Guesnerie (Collége de France, Paris), a group of critics of the Rational Expectations Hypothesis (REH), notably in the study of financial markets and macroeconomies, has come together to organize the International Network on Expectational Coordination (INEXC). The first objective of the INEXC is to provide support for the dissemination of knowledge through conferences, workshops, and exchanges of visitors. The second objective is to attract and support the work of younger colleagues who wish to pursue alternative approaches to expectational coordination issues, particularly high-risk high-expected return approaches. A more detailed description of purpose for INEXC can be found here.

• The Modelling Social Systems discussion group, active at the University of Southampton (UK) through 2015, compiled a Listing of ABM Resources consisting of Agent-Based Modeling (ABM) materials that discussion group members found to be helpful and influential introductions to ABM.

• The Computational Modeling for SocioEcological Science (CoMSES) Network is a scientific research coordination network to support and expand the development and use of computational modeling in the social and life sciences. OpenABM is a node in the CoMSES Network, providing a growing collection of tutorials and FAQs on agent-based modeling, a model library intended to provide a locus for authors and modelers to share their models, and forums for modeling-related discussions and job postings.

• Rethinking Economics is an international network of economics students, thinkers and citizens, including those with no previous training in economics, who are organising to create fresh economic narratives to challenge and enrich the predominant neoclassical narrative. The professed aim of the network is "to demystify and diversify economics in the public eye; to educate ourselves and other students in a more reflective economics; to inspire divergent economists to engage with one another in debate; and to promote a politics of responsibility with academic economists." Additional organizers and collaborators are actively being sought.

Sites of Particular Interest for ACE

• A website on Agent-Based Computational Economics, maintained by Leigh Tesfatsion (Economics, Iowa State University), provides pointers to various ACE-related resources, including: surveys; an annotated syllabus of readings; software and toolkits; interactive computer demos; journals; and pointers to individual researchers and research groups.

• A website on Agent-Based Modeling of Restructured Electricity Markets has been constructed by Leigh Tesfatsion (Economics, Iowa State University). Resources provided at this site include a listing of key issues, readings, software, and pointers to individual researchers and research groups.

• The Agent-Mediated Electronic Marketplaces Lab (AMEM), under the direction of Tuomas Sandholm (Carnegie Mellon University), studies how computers impact traditional game theory. This involves everything from large-scale equilibrium computation to automated negotiation to the design of new economic structures such as markets.

• Nicholas Gessler (Duke University, NC) maintains an interesting unusual website titled Complex Evolutionary Multiagent Systems. Resources provided at this student-oriented site include course syllabi, conference information, numerous illustrative executable simulations in C++ (with links, explanations, source code, and zipped Borland project files), and tutorial materials covering simulation basics.

• The Artificial Intelligence Economic Research Center (AI-ECON) was established in 1995 at the College of Social Sciences, National Chengchi University. The goal of the center is to fully harness computer power to facilitate the integration of economics into a multidisciplinary research stream permitting cross-fertilization of ideas.

• The Cognitive and Experimental Economics Laboratory (CEEL), Department of Economics, University of Trento, Trento, Italy maintains a website providing general information about its experimental and computational activities.

• Peer-Olaf Siefers (University of Nottingham, UK) is the organizer of a Special Interest Group (SIG) called the Behavioural Economics Meets object oriented Simulation SIG (BEMooSSIG). The BEMooSSIG is a discussion forum for people interested in studying how to use games (lab experiments) as a data collection tool or as a mechanism to inform/support modeling the decision making of actors in object oriented social or socio-technical system simulation models and how the simulation results can be used to cross-validate game results.

• Al Roth (Stanford University) maintains an extensive informative web site on Game Theory, Experimental Economics, and Market Design.

• Mike Shor (Owen Graduate School of Management, Vanderbilt University) has developed a Game Theory Resource Site for educators and students of game theory. The site includes pointers to lecture notes, news, interactive materials, text book reviews, pop culture use of game theory, games, quizzes and tests, and related links.

• The Interdisciplinary Center for Economic Science (ICES) at the Arlington, Virginia campus of George Mason University uses human-subject laboratory experiments to test economic theories. The ICES moved to GMU in 2001 from the University of Arizona, where it was known as the Economic Science Laboratory.

• The LABORatorio Riccardo Revelli, associated with the University of Torino and funded by the Compagnia di San Paolo, uses agent-based models to study labor market and industrial dynamics issues. Issues of particular interest include the operation of European labor markets, and the evaluation of policy options aimed at dealing with employment problems in the EU.

• Paul M. Torrens (Department of Geography, University of Utah) maintains a website on Geosimulation. Linked resources include projects focusing on adaptive industrial and business networks, urban change, pedestrian behavior, and suburban sprawl, as well as a variety of open-source cellular automata and agent-based modelling platforms.

• The Economics Web Institute is a growing hyper-text document maintained by Valentino Piana (Tiscali, Italy) that integrates downloadable simulation models, real data, and theoretical reflections. It's aim is to apply evolutionary economics and agent-based computational economics approaches to standard problems of microeconomics and macroeconomics.

• The Society for Computational Economics (SCE) supports research activities related to computational economics, the intersection between economics and computation. Included within computational economics are a variety of special interest groups focusing on areas such as agent-based computational modeling, computational econometrics and statistics, computational finance, computational modeling of dynamic macro systems, computational tools for the design of automated Internet markets, programming tools specifically designed for computational economics, and pedagogical tools for the teaching of computational economics. Resources available at the SCE home page include conference information, special interest group contact information, journal and book pointers, information regarding the SCE graduate student paper contest, and instructions for joining the SCE.

• The Association for Evolutionary Economics (AFEE) is an international organization of economists and other social scientists devoted to the analysis of economies as evolving, socially constructed, and politically governed systems. The intellectual heritage of AFEE is that of the original institutional economics created and developed by early twentieth-century economists such as Thorstein Veblen, John R. Commons, and Wesley Mitchell. The AFEE sponsors the Journal of Economic Issues, published quarterly, whose primary mission is to present articles that use and develop the core ideas of institutional economics in discussions of current economic problems and policy alternatives.

• The Institute for New Economic Thinking (INET) is a nonpartisan, nonprofit organization devoted to developing and sharing the ideas that can repair our broken economy and create a more equal, prosperous, and just society. To meet current and future challenges, we conduct and commission research, convene forums for exchanging ideas, develop curricula, and nurture a global community of young scholars.

• The The Innovation, Knowledge and Economic Dynamics Research Group (IKE) is a research group at Aalborg University Business School (AAUBS). The IKE group was established in 1977 and has evolved into a long-term research program on innovation, knowledge, and economic dynamics.

• The Society for Computer Simulation (SCS) International is a technical society devoted to the advancement of simulation and allied computer arts in all fields. The purpose of the society is to facilitate communication among professionals in the field of simulation. To this end, the society organizes meetings of regional councils, sponsors and co-sponsors national and international conferences, and publishes a monthly technical journal, Simulation, as well as a quarterly journal, the Transactions of the Society for Computer Simulation. Membership in the SCS is open to all who are or have been professionally engaged in the field of simulation.

Economic and Social Network Formation

• A site titled Formation of Economic and Social Networks is maintained by Leigh Tesfatsion (Economics, Iowa State University). See this site for an extensive list of annotated pointers to on-line network research, including: introductory readings; research sites; software, toolkits, and computer demos; books and journals; and resource sites, groups, and individual researchers.

• A site devoted more specifically to agent-based research focusing on the Formation and Evolution of Interaction Networks is maintained by Leigh Tesfatsion (Economics, Iowa State University). See this site for an extensive list of annotated pointers to on-line agent-based network research, including: introductory readings; general readings; software, toolkits, and computer demos; and resource sites, groups, and individual researchers.

Evolution

• Edge Foundation, Inc. was established in 1988 as an outgrowth of a group known as the Reality Club. The mandate of the Edge Foundation is to promote inquiry into, and discussion of, intellectual, philosophical, artistic, and literary issues, as well as to work for the intellectual and social achievement of society. The Edge World Question Center contains contributions from a variety of researchers whose work relates to complex systems and evolutionary modeling, such as Jared Diamond, J. Doyne Farmer, W. Daniel Hillis, Steven Pinker, Richard Dawkins, Rodney Brooks, Stephen Grossberg, Andy Clark, Freeman Dyson, Daniel Dennett, Stuart Kauffman, and Kevin Kelly, among many others.

• The Richard Dawkins Foundation for Reason and Science (US) maintains a website devoted to the support of scientific education, critical thinking, and evidence-based understanding of the natural world, inspired by the work of Richard Dawkins. Site resources include news items, books, writings, quotes, videos, software, biographical information, and links.

Complex Adaptive Systems

• The New England Complex Systems Institute (NECSI) New England Complex Systems Institute (NECSI), established in 1997 by a group of faculty in the New England area, is an independent educational and research institution dedicated to advancing the study of complex systems.

• The Los Alamos National Laboratory's Center for Nonlinear Studies, formed in 1980, organizes research related to nonlinear and complex systems phenomena.

• The Center for the Study of Complex Systems (CSCS) at the University of Michigan is a broadly interdisciplinary program designed to encourage and facilitate research and education in the general area of nonlinear, dynamical, and adaptive systems.

• The mission of the Center for Connected Learning and Computer-Based Modelling (CCL) at Northwestern University, Evanston, Illinois is to create tools that will help learners (at all levels) to make greater sense of complex phenomena, and to study how learners come to understand complexity. In particular, a concrete goal of this center is to develop "object-based parallel modeling languages" (aka agent-based or multi-agent) that can be used by learners to create rich and detailed models of large systems of interacting agents and objects. The center maintains and updates the freely available modeling environments: NetLogo (multi-platform) and StarLogoT (available only for the Macintosh).

• Kolmogorov complexity Website maintained by Ming Li and Paul Vitanyi of CWI (Centrum voor Wiskunde en Informatica) in the Netherlands.

• The Mobile Robots Group (MRG) at the Department of Artificial Intelligence at the University of Edinburgh in the United Kingdom. The MRG is a loose collection of staff and students who share the view that artificial intelligence will best be understood by using behaviour-based architectures to construct agents that live autonomously in the real world. Resources available at this site include research papers, course materials, robot descriptions, and related links.

• Networks and Agent Networks (NaN) is a research group spanning various units at Indiana University-Bloomington, including informatics, cognitive science, physics, computer science, information science, and social science. The group is interested in exploring broad areas of complex systems that involve networks issues.

• The Computer Graphics Group at the Institute of Computer Graphics and Algorithms, Vienna University of Technology, performs basic and applied research in computer graphics. Areas of focus include scientific visualization, virtual environments, and computer animation. In addition to research, the group specializes in consulting and technology transfer as well as computer graphics-related education at both the undergraduate and graduate levels.

• The Society for Modeling and Simulation International is a nonprofit volunteer-driven corporation established in 1952. It is dedicated to advancing the use of modeling and simulation to solve real-world problems. The society publishes the journal Simulation as well as the Modelling and Simulation magazine.

• The International Microsimulation Association (IMA) , launched in 2005, aims to promote the free interchange of experiences and ideas etween practioners of microsimulation worldwide. The IMA publishes the peer-reviewed online journal The International Journal of Microsimulation.

Artificial Life and Artificial Intelligence

• A research group at the MIT Media Laboratory, led by Professor Rosalind Picard, maintains a website titled Affective Computing. Affective computing is defined as "computing that relates to, arises from, or deliberately influences emotion." The research highlighted at this site "focuses on creating personal computational systems endowed with the ability to sense, recognize, and understand human emotions, together with the skills to respond in an intelligent, sensitive, and respectful manner toward the user and his/her emotions."

• Andrew Hodges, author of Alan Turing: The Enigma, maintains a site devoted to the work of Alan Turing (1912-1954), titled the Alan Turing Home Page.

• Thomas S. Ray (Zoology, University of Oklahoma, Norman, OK) maintains an interesting resource site on his seminal Tierra digital evolution software at the Tierra Home Page.

• The International Society for Artificial Life (ISAL) provides links to various resources pertaining to the study of artificial life, including news, conferences, journals, and software releases.

• Biota.org, a special interest group of the Contact Consortium (a not-for-profit membership and research organization based in Scotts Valley, California), hosts a website featuring Karl Sims' Evolving Virtual Creatures. Sims' famous creatures evolve their morphology (body structure) over time in an attempt to accomplish various set tasks. Visitors to this site can view stills of these creatures in competition and in locomotion at successive evolutionary time steps. Instructions for obtaining the original MPEG movie of Sims' creatures in motion are also given.

• Framsticks is a three-dimensional artificial life simulation project. Both physical structure of creatures and their control systems are evolved. Evolutionary algorithms are used with selection, crossovers, and mutations. Finite elements method is used for simulation. Both spontaneous and directed evolutions are possible."

• The Oz Project Archive maintained at Carnegie Mellon University reports on a now-inactive project whose objective was to develop technology and art to help artists create high quality interactive drama based in part on artificial intelligence technologies. A key objective was to build believable agents in dramatically interesting micro-worlds.

• Will Wright (inventor of SimCity), together with other colleagues at Maxis, developed more than a dozen computer simulation games, many related to architecture and city planning. Wright's release called "The Sims" is an elaborate Tamagotchi-style neighborhood that allows players to freely manipulate their virtual inhabitants. For more information about The Sims, visit The Sims Website.

• UMBC AgentWeb is a web site featuring extensive information and resources about intelligent information agents, software agents, softbots, knowbots, and infobots, among other related concepts.

Learning and Human Cognition

• The Agents Learning About Agents web site is dedicated to the study of what happens when agents (i.e., pro-active, goal-driven, selfish, independent software/hardware constructs) start to learn about each other, especially if they do so in order to gain a competitive advantage over other agents. Resources available at this site include pointers to classes, laboratories, and other web sites useful for this topic area.

• The Autonomous Learning Laboratory (ALL), originally founded and co-directed by Andrew G. Barto and Sridhar Mahadevan, carries out foundational interdisciplinary research on machine learning and computational models of biological learning. Autonomous learning refers to what a self-reliant agent must do to learn from its own experiences. The long-term goals of the laboratory are to develop more capable artificial agents, to improve our understanding of biological learning and its neural basis, and to forge stronger links between studies of learning by computer scientists, engineers, neuroscientists, and psychologists. Areas of interest include reinforcement learning, machine learning, abstraction, hierarchy, motor control, robotics, computational neuroscience and developmental psychology.

• The Center for Adaptive Behavior and Cognition (ABC) was founded by Prof. Dr. Gerd Gigerenzer at the Max Planck Institute in Berlin. ABC encompasses an interdisciplinary and international research group focusing on the following key question: How do humans and other animals make decisions under uncertainty, that is, when time and information are limited and the future is unknown?

• The Center for Research on Concepts and Cognition (CRCC) at Indiana University is an interdisciplinary center for research in cognitive science directed by Douglas Hofstadter. CRCC research focuses mainly on emergent computational models of creative analogical thinking and its subcognitive substrate -- namely, fluid concepts. The group also conducts research (mostly non-computational) in a number of other areas of cognitive science, including error-making, creative translation, scientific discovery, musical composition, the comprehension and invention of jokes, the nature of sexist language and default imagery, philosophy of mind, and foundations of artificial intelligence.

• Stan Franklin, Professor of Mathematical Sciences at the University of Memphis, Tennessee, and well-known author of Artificial Minds (MIT Press, 1995), maintains a web site on Conscious Software: A Computational View of Mind. From the web site introduction: "By a `conscious' software agent we mean a cognitive agent (an autonomous agent with human-like cognitive features) designed within the constraints of Baar's global workspace theory of consciousness. Like the Roman god Janus, the conscious software project has two faces, its science face and its engineering face. Its science side will flesh out the global workspace theory of consciousness, while its engineering side explores architectural designs for information agents that promise more flexible, more human-like intelligence within their domains." Accounts of various conscious software projects by Franklin and his collaborators can be found at the Conscious Software web site.

• Seminal work by Adrian Thompson (COGS, University of Sussex, UK) and other researchers on Evolvable Hardware. is discussed at this site.

• A repository of resources on the use of artificial intelligence (AI) in the design of games can be found at the AI Game Programmers Guild Homepage. This site stresses practical approaches to the problem of building better computer opponents and is aimed at both game developers and game players.

• The Laboratory for Natural and Simulated Cognition (LNSC) at McGill University in Montreal, Canada, investigates human cognition through a combination of psychological and computational approaches. Basic psychological phenomena are simulated in a connectionist framework, often leading to predictions that are tested with humans. Current projects concern cognitive development, interactions between knowledge and learning, techniques for analyzing knowledge representations in neural nets, and cognitive consistency phenomena in social psychology.

• Leigh Tesfatsion (Economics, Iowa State University, Ames, IA) maintains a website title Learning and the Embodied Mind. Resources at this website include annotated pointers to tutorials, general readings, software, research groups, and individual researchers.

• Leigh Tesfatsion (Economics, Iowa State University, Ames, IA) maintains a website title Learning Via Criterion Filtering. Criterion filtering is the direct updating of criterion functions on the basis of transitional reward assessments in analogy to Bayes' Rule for the updating of probability distributions on the basis of transitional probability assessments.

• MIT CogNet is an electronic community for the cognitive and brain sciences under development by the MIT Press. The intention is to bring together current and classic resources in the field and provide a unique, interactive forum for scholars, students, and professionals. Services will include: a searchable full-text library with a growing collection of books, journals, and other reference works; an academic almanac of cognitive science programs; editorials on groundbreaking or controversial research; job listings; virtual poster sessions; threaded discussion groups; and community member profiles. MIT CogNet is a free service through August 31, 2000, and is actively seeking charter members.

• The Stanford Encyclopedia of Philosophy Web Site, maintained at Stanford University (Palo Alto, California), is a dynamic encyclopedia of entries for all areas of philosophy, including many entries relevant to agents, cognitive science and AI.

• The Social Psychology Network is an extensive database on social psychology maintained by Scott Plous (Weslyan University) and supported by the National Science Foundation. The database provides more than 5,000 links to psychology-related resources. The database can be searched by topic or keyword.

• The Tangible Media Group at the MIT Media Laboratory (Cambridge, Massachusetts), founded and directed by Hiroshi Ishii, focuses on the design of seamless interfaces between humans, digital information, and physical environments. From Hiroshi Ishii: "People have developed sophisticated skills for sensing and manipulating our physical environments. However, most of these skills are not employed by traditional Graphical User Interface (GUI). Tangible Bits, our vision of Human Computer Interaction, seeks to build upon these skills by giving physical form to digital information, seamlessly coupling the dual worlds of bits and atoms. Guided by the Tangible Bits vision, we are designing `tangible user interfaces' which employ physical objects, surfaces, and spaces as tangible embodiments of digital information. These involve foreground interactions with graspable objects and augmented surfaces, exploiting the human senses of touch and kinesthesia. We are also exploring background information displays which use `ambient media' ---- ambient light, sound, airflow, and water movement. Here, we seek to communicate digitally-mediated senses of activity and presence at the periphery of human awareness. Our goal is to realize seamless interfaces between humans, digital information, and the physical environment taking advantage of the richness of multimodal human senses and skills developed through our lifetime of interaction with the physical world."

Evolutionary and Adaptive Computation

• Leigh Tesfatsion (Iowa State University, Ames) maintains a website titled Adaptive Computation Methods for Nonlinear Systems. Methods (with software implementations) featured at this site include: nonlocal automated sensitivity analysis (NASA), for the tracking of solutions for parameterized nonlinear systems over parameter intervals; tracking of eigenvalues and eigenvectors for parameterized matrices over parameter intervals; adaptive homotopy continuation; and the FEED algorithm for the fast efficient evaluation of higher-order partial derivatives.

Demos, Software, and Software Development

• A separate resource site devoted to interactive demos is now maintained by Leigh Tesfatsion (Economics, Iowa State University), titled ACE/CAS Comp Labs and Demonstration Software.

• A separate resource site devoted to software and software development is now maintained by Leigh Tesfatsion (Economics, Iowa State University), titled ACE/CAS General Software and Toolkits

• Floating Point Arithmetic and Agent-Based Models

  When doing arithmetic on a computer, the uncountably infinite set of real numbers must somehow be squeezed into a discrete set of isolated numbers represented in binary floating-point format. The resulting floating-point errors can lead to some unpleasant surprises for the unwary. For example, floating-point addition does not obey the associative law, e.g., (0.1 + 0.2) + 0.3 can fail to equal 0.1 + (0.2 + 0.3). Moreover, summing 0.05 twenty times can yield a total that differs from 1. In both cases the problem can be traced to the fact that simple-looking base-10 numbers such as 0.1 are not exactly representable in binary floating-point format because they correspond to infinitely repeating binary numbers.

  Researchers at the Macaulay Land Use Research Institute (MLURI) in Aberdeen, Scotland -- now known as the James Hutton Research Institute -- have conducted a number of important and interesting studies to investigate the effects of floating-point errors in agent-based models implemented in FEARLUS. A summary of these efforts, with pointers to related papers and demos, can be accessed here. See, in particular, a January 2005 JASSS paper by three MLURI researchers, Gary Polhill, Luis R. Izquierdo, and Nicholas M. Gotts, titled "The Ghost in the Machine (and Other Effects of Floating Point Arithmetic". This paper investigates the effects of floating-point errors in a model of land use change and in the Santa Fe Artificial Stock Market model.

  The MLURI researchers concluded that floating-point errors are not likely to be of major importance if a model does not perform many operations and if it does not contain branching statements. However, on a personal note, I would like to warn about the need to be careful also about imported utilities such as pseudo-random number generators. In my ISU electricity research group we discovered that a major java source file (EmpiricalWalker.java) in the well-known and frequently imported cern.jet.random package is disastrously susceptible to floating-point addition errors.

Miscellaneous Sites of Possible Interest

• Supported by the Network Cybernetics Corporation (Dallas, Texas), the Robots.Net Site provides current news on personal and industrial robotics, robot competitions, and a variety of other robot-related events.

• In collaboration with others, Robert Bernard and other researchers at PricewaterhouseCoopers Consulting have worked to develop software called CommunityViz as an aid for community planning. This software was featured in an article titled "SimCity, Real Life" in Newsweek (August 5, 2002). The core forecasting component of CommunityViz, called the Policy Simulator, is an agent-based model to be tailored to the specifications of whatever community is under study. A White Paper describing the Policy Simulator is available at the CommunityViz Home Page.

• The Artificial Intelligence Applications Institute (School of Informatics, University of Edinburgh) was established in 1984 to encourage the development and use of artificial intelligence methods in practical applications.

• The constructive approach to mathematics is enjoying a resurgence among mathematicians, due in large part to the growing power of computers. The Stanford Encylopedia of Philosophy provides an extended 20-page discussion of constructive mathematics that might be of interest to agent-based computational modelers.

  As explained in this encylopedia entry, constructive mathematics is distinguished from its classical mathematical counterpart by its strict interpretation of the phrase "there exists" to mean "one can construct." For example, consider the statement "there exists an object x with property P." For a constructive mathematician, a proof of this statement requires that an algorithm be exhibited that constructs x and demonstrates, by whatever calculations are necessary, that x has property P. In contrast, for a classical mathematician, the proof of this statement could also be established by a "proof by contradiction," i.e., a demonstration that the negation of the statement induces a contradiction of something known (or assumed) to be true, with no actual construction of x.

• Roland Gunesch (Mathematics, University of Hamburg, Germany) maintains a web site on Entropy on the Worldwide Web. The goal of this web site, as conceived by its original developer Chris Hillman (Ph.D. in Mathematics, University of Washington), is to promote appreciation, understanding, and applications of entropy. Resources include a brief overview of entropy as well as pointers to journals, conferences, research groups, software, expository articles, textbooks, and suggested readings in a variety of specific disciplines.

• Jay Scott (The Math Forum, Swarthmore, Pennsylvania) maintains a web site on Game-Playing Computers for artificial intelligence researchers and game programmers. The main focus is on how computers can learn to get better at playing games. The site provides descriptions for a variety of game-playing programs that rely on heuristic search algorithms, neural networks, genetic algorithms, temporal differences, and other methods, including programs for robotic soccer, backgammon, pursuit-evasion games, and chess. In addition, the site provides pointers to tutorials, individual researchers, and related web sites.

• Adam Smith (1723-1790) was a Scottish political economist and philosopher whose most famous work (The Wealth of Nations, 1776) laid the foundations for laissez-faire (free-market) economic theory. In this work he coined the term "invisible hand" for a situation in which economic traders, pursuing only their own self interest, nevertheless manage to self-organize in ways of benefit to society as a whole. The Adam Smith Global Foundation, launched in 2012 in Adam Smith’s birth town of Kirkcaldy, provides pointers to many source materials relating to Smith's work.

• The CoMSES Net/OpenABM Consortium is a group of researchers, educators, and professionals with a common goal -- improving the way agent-based models are developed, shared, and utilized. The organizers are currently developing a model archive to preserve and maintain digital artifacts and source code comprising an agent-based model. Developers are encouraged to add their models to the model archive (prior member registration required).

• Random.Org offers "True Random Numbers" to anyone on the Internet. The numbers are generated using atmospheric noise from a radio. All generated numbers are tested statistically and the results posted in real-time mode. The site is maintained by Mads Haahr (Computer Science, University of Dublin, Tinity College, Ireland).

Copyright © Leigh Tesfatsion. All Rights Reserved.