Link to this blog post: http://raffysaldana.blogspot.com/2009/09/notes-on-complex-systems-and.html
"Science has explored the microcosmos and the macrocosmos; we have a good sense of the lay of the land. The great unexplored frontier is complexity"
-- Heinz Pagels, "The Dreams of Reason"
Recently, the Ateneo de Manila University (AdMU) Innovation Center headed by Dr. Gregory Tangonan started a complex systems study group. This semester (1st semester, school year 2009-2010) the Electonics, Communications and Computer Engineering (ECCE) Department under the School of Science and Engineering offered a graduate course on "Complex Systems" with me as one of the facilitators (together with Dr. Greg Tangonan and Dr. Nathaniel Libatique, Chair of the ECCE).
My particular interest in the topic of complex systems is on modeling and simulation. As of this writing, I am involved in a research project dealing with complex systems dynamics of evolutionary trade models and international development.
To aid my students and my research group on complex systems (and other interested readers) I am putting online some of my notes on this topic.
NOTES ON COMPLEX SYSTEMS AND EVOLUTIONARY TRADE MODELS
(Note: This is a work in progress. References will be supplied later.)
Part I. Introduction to Complex Systems
Part II. Complex Systems and Economics
Part III. An Evolutionary Theory of Trade
Part IV. Incorporating Technological Productivity in the Evolutionary Trade Model
Part V. A Cellular Automaton Model of Evolutionary Trade
Part VI. Non-Equilibrium, Spatial Evolutionary Trade Models
Part VII. Case Study: Modeling the Impact of Changes in Transportation Cost in India
Part VIII. Case Study: A 'Policy Impact Model' for Nepal
Part IX. Agent-Based Computational Economics
Part I. Introduction to Complex Systems
• Complex systems is a scientific field which studies the common properties of systems that are considered fundamentally complex. Such systems are used to model processes in biology, economics, physics and many other fields.
• It is also called complex systems theory, complexity science, study of complex systems, sciences of complexity, non-equilibrium physics, and historical physics.
• The key problems of complex systems are difficulties with their formal modeling and simulation. From such perspective, in different research contexts complex systems are defined on the base of their different attributes.
• Since all complex systems have many interconnected components, the science of networks and network theory are important aspects of the study of complex systems. At present, the consensus related to one universal definition of complex system does not exist yet.
• Complex Systems is a new approach to science that studies how relationships between parts give rise to the collective behaviors of a system and how the system interacts and forms relationships with its environment.
• Complex systems have multiple interacting components whose collective behavior cannot be simply inferred from the behavior of components. The recognition that understanding the parts cannot explain collective behavior has led to various new concepts and methodologies that are affecting all fields of science and engineering, and are being applied to technology, business and even social policy.
In the book "Complexity A Guided Tour", Melanie Mitchell (2009) observed that complex systems have three common properties:
1. Complex collective behavior: Complex systems consist of large networks of individual components, each typically following relatively simple rules with no central control or leader. It is the collective actions of vast numbers of components that give rise to the complex, hard-to-predict, and changing patterns of behavior.
2. Signaling and information processing: All complex systems produce and use information and signals from both their internal and external environments.
3. Adaptation: All complex systems adapt – that is, change their behavior to improve their chances of survival or success – through the learning or evolutionary processes.
From these three properties, Mitchell (2009) proposed a definition of the term complex system: a system in which large networks of components with no central control and simple rules of operation give rise to complex collective behavior, sophisticated information processing, and adaptation via learning or evolution.
In the book "Handbook of Research on Complexity" edited by J. Barkley Rosser, Jr. (2009), six characteristics of the lowest level of complexity are mentioned:
1. Dispersed interaction among heterogeneous agents acting on each other locally in some space,
2. No global controller that can exploit all opportunities or interactions, despite the possibility of some weak global interactions,
3. Cross-cutting hierarchical organization with tangled relations,
4. Continual adaptation and learning by evolving agents,
5. Perpetual novelty as new markets, technologies, behaviors, and institutions create niches in the ecology of the system, and
6. Out-of-equilibrium dynamics with either zero or many equilibria existing, and the system unlikely to be near a global optimum.
Next Topic: Complex Systems and Economics