Madison Chaos and Complex Systems Seminar

Fall 1994 Seminars

September 15. Organizational meeting with brief introductions.
September 21. Prof. Ian Dobson, UW Madison, Electrical and Computer Engineering. ``Avoiding Complex Behavior in Dynamical Systems.''

No abstract.

September 28. Prof. Barrett Caldwell, UW Madison, Industrial Engineering. ``Feedback Systems and Organizations: Chaos, Complexity, and Communication.''

Abstract: This presentation outlines conceptual and methodological issues in applying feedback and sociotechnical systems approaches to information technology (IT) adoption and use in organizations. The impact of "chaos theory" or nonlinear dynamic analysis has spread into a variety of the physical and social sciences. Some macroergonomics researchers have applied "chaos" principles to the organizational design and management of new IT's. As IT systems develop in more technological complexity and diffusion in and across organizations, significant problems exist in coordinating technological capability with organizational demands and the social environment of the workplace. This presentation addresses these issues of chaos and complexity (both metaphoric and mathematical) in terms of communications dynamics of information exchange and feedback control.

October 5. Matthew Lazzara, UW Madison, Dept. of Atmospheric and Oceanic Sciences. ``Chaos and Atmospheric Predictability.''

Abstract: This talk will introduce the basic theory of chaos and how it affects the atmospheric prediction problem. Physical examples will be used to illustrate the basic concept of nonlinear effects and initial condition sensitivity. Dr. Edward N. Lorenz's model of chaos is briefly discussed. The results hold great implications of chaos theory towards the atmospheric weather prediction problem. Having noted this, possible solutions are explored using the Monte Carlo, and lagged-averaged forecasting methods. A new technique, Breeding Growing Modes (BGM), will be mentioned. Finally, ``Lorenz Trees'' will be discussed as a way of viewing how good predictions are.

October 12. Prof. Joel Robbin, UW-Madison Math Department. ``Symbolic Dynamics and Hyperbolic Chaos.''

No abstract.

October 19. Prof. Anastasios Tsonis, UW-Milwaukee, Dept. of Geosciences. ``An investigation of the ability of nonlinear methods to infer dynamics from observables.''

Abstract:In this study analysis of data whose character was kept secret was performed by employing a variety of nonlinear approaches. The idea was to test the ability of approaches stemming from the theory of nonlinear dynamical systems to infer the true properties hidden in the data. The approaches employed include dimension estimation, nonlinear prediction, Lyapunov exponent estimation and false nearest neighbors. It is concluded that even though the methods have problems and occasionally may be inconclusive, when correctly applied they are effective in delineating the dynamics underlying the data.

October 26. Melanie Mitchell, Director of the Adaptive Computation Program at the Santa Fe Institute. ``The Evolution of Emergent Computation.''

Abstract:How does evolution produce sophisticated emergent computation in systems composed of simple components limited to local interactions? In this talk I will describe a model of such a process, in which a genetic algorithm was used to evolve cellular automata to perform computational tasks requiring globally-coordinated information processing. A number of quite sophisticated novel computational strategies was discovered. I will analyze the emergent logic underlying these strategies in terms of information processing performed by ``particles'' in space-time, and describe in detail the temporal mechanisms by which the genetic algorithm discovered these strategies. This analysis is a preliminary step in understanding the general mechanisms by which sophisticated emergent computational capabilities can be automatically produced in decentralized multiprocessor systems.

November 2. Erica Jen, Los Alamos National Laboratory and the Santa Fe Institute. ``Particles and Backgrounds in Cellular Automata.''

No abstract.

November 9. Prof. Dietrich Uhlenbrock, Math Dept, UW-Madison. ``Chaos software.''

Abstract: This talk promises to have glitzy hardware and pretty pictures [verbatim!]. Also, this will be kind of a ``consumer report'' for people interested in software to analyze dynamical systems.

November 23. Fred Brauer, UW-Madison Math Department. ``Chaos and catastrophe in a simple delayed - recruitment population model.''

Abstract: We study the behavior of a differential-difference equation which models a population in which the birth and death rates depend on adult population size and there is a fixed maturation time, under the action of constant - yield harvesting. Oscillations and chaotic behavior are possible in some situations if the if the maturation time is long enough. Harvesting tends to stabilize the system, but excessive harvesting leads to catastrophe.

November 30. Prof. Blake LeBaron, UW-Madison, Dept. of Economics. ``Are Stock Prices Chaotic?''

Abstract: This talk will cover some of the techniques used for analyzing time series, and determining whether they are chaotic. It will stress what can actually be discovered by looking at a time series when the researcher has little guidance about what sort of dynamical system may be present. Data from the stock market is used to show what sorts of problems may be encountered and some pitfalls to avoid. The talk will finish with a discussion of noisy chaos and how it is important for researchers looking at many real world time series.

December 7. Prof. David Griffeath, UW-Madison Math Department. ``High- and Low- End Platforms for Interactive Simulation of Complex Spatial Systems.''

Abstract: For the past two years I have been working, with Bob Fisch, on the development of effective, interactive simulation tools for the study of complex lattice dynamics. We are designing two platforms in parallel:

  1. a high-end simulator based on the new CAM8 cellular automaton machine from MIT (Margolus and Toffoli);
  2. a low-end (MS) Windows simulator and graphical front end called WinCA.

My presentation will demo the current beta version of WinCA and describe some of our first CAM8 experiments. The ultimate goal is to combine the ease of use of WinCA with the performance power of CAM8. A recently funded NSF ``Ecomachine'' project seeks to apply this design combination to the study of spatial ecology models.

December 14. Summary and wrap up meeting. Changes for the Spring.
Up to the Chaos and Complex Systems Seminar page.
Last changed 24 January 1995 [CRS]