Chaos and Complex Systems Seminar
Fall 1996 Seminars
Dates, speakers, titles and abstracts will be listed as they become
Meetings will be noon Tuesdays in 4274 Chamberlin Hall unless
- 3 September. Steering Committee
- 10 September. Bill Lytton: ``The
Complex Cell or Simple Network?''
- 17 September. Jean-Paul Chavas:
- 24 September. Scott Kelso: ``How
The Problem of Coordination.''
- 1 October. W. A. Brock: ``Evolutionary
the Stock Market.''
- 8 October. Chris Demarco. ``Predicting
in Large Scale Electric Power Networks: the Anatomy of
- 15 October. Rick Jenison: ``Dynamic
of Time-to-Arrival from Acoustic Information.''
- 22 October. Bob Savit: ``Time
- 29 October. David Albers: ``Dynamical
Artificial Neural Networks with Random Weights.''
- 5 November. Richard Belew: ``Competitive
- Related Lecture: 11 November.
``The Role of Brain Oscillations in Long Term and Short Term
- 12 November. Robert Meyer: ``A Genetic
Optimal Domain Decomposition.''
- Related Lecture: 15 November.
``Brain Circuitry of Memory and Memory Loss: Findings from
- Realted Lecture: 15 November.
- 19 November. Paul Terry: ``Impeding
From Fusion Reactors to the Ozone Hole.''
- 26 November. George Hrabovsky:
- Related Lecture: 26 November.
``Quantifying the Complexity of Superscalar Processors.''
- 3 December. Virginia Young: ``Creating
from Linguistic Rules--A Fuzzy Logic Approach.''
- 10 December. Christopher Kribs: ``A
with Recruitment and Activity Levels.''
3 September. Steering Committee Meeting
Speaker nomination and recruitment. Funding. Possible themes for
10 September. Bill Lytton, UW Neurology.
Oscillator: Complex Cell or Simple Network?''
Abstract: Neurons are complex dynamical systems with multiple
interactions that are presumably relevant to their information
role. We have used computer modeling to investigate the neurons of
thalamus, a central nuclear complex that serves both as a
sensory input and as a central oscillator during sleep. Three main
types make up the thalamic network: thalamocortical cells (TC),
cells (RE) and thalamic interneuron (INT). Depending on membrane
each neuron type can by itself produce oscillatory behavior.
together, they influence each other's phase and frequency to produce
oscillatory patterns of the thalamus as a whole.
17 September. Jean-Paul Chavas, UW
``Dynamics and Economic Rationality.''
Abstract: Economic rationality and efficient resource
are typically defined in the context of optimizing behavior. This
the question: Under what conditions does optimizing behavior
dynamics (e.g., convergence to a steady-state equilibrium)? And
conditions does it generate complicated dynamics (e.g., limit cycles
chaos)? Implications are discussed concerning the formulation and
of dynamic optimization problems, the explanation of business
the characterization of economic rationality.
24 September. J. A. Scott Kelso, Center for
Systems, Florida Atlantic University. ``How Things Work Together:
Abstract: Coordination is a fundamental feature of living
implying some kind of functional order in which the ``whole is
than and different from the parts''. Historically, ideas from
Bernstein's synergy concept, Weiss's notion of self-differentiation,
Holst's principle of central coordination are all attempts to come
with the coordination problem. Only recently have these intuitions
provided a firm theoretical and empirical foundation. Building upon
concepts and methods of pattern formation in nonequilibrium systems,
dynamics aims to find the basic rules for how coordination states
and change. The first part of this talk reviews some research in
it has been possible to identify relevant coordination variables and
dynamics for several different kinds of system (e.g. parts of the
the organism responding to signals from its environment, organisms
with each other). Importantly, predictions of the theory have been
to experimental tests, a process that has led to new theoretical
The second part of the talk will describe how the strategy of
dynamics, in which instability plays a key conceptual and
role, has been extended to the study of how parts of the brain are
with each other and with behavior itself. Work is underway that
to derive earlier phenomenological models of brain and behavioral
from a deeper theory grounded in current knowledge about cortical
and neurophysiology. If there is time, I will talk about what all
might mean for the coordination of mind, brain and behavior.
1 October. W. A. Brock, UW Economics.
Theories of the Stock Market.''
Abstract: This talk gives a tour of recent efforts to modify
standard rational expectations literature to include expensive
of rational expectations. For financial models fitness of an
or belief system is past trading profits net cost of acquisition.
of fitnesses changes over time. There are periods where markets run
and periods where they run ``loose.'' This is so because if everyone
expensive but more accurate expectations then the profit is competed
to the extent that the acquisition cost is not covered and vice
This tension can create complicated dynamics. A discussion will be
of problems that deterministic dynamical systems models face in
patterns that look like real stock market data.
8 October. Chris Demarco, UW Electrical and
Engineering. ``Predicting Dynamic Behavior in Large Scale Electric
Networks: the Anatomy of Blackout.''
Abstract: The North American electric power network is
of hundreds of thousands of electromechanical devices, coupled by a
grid of continental scale. The composite behavior of this huge
system can be highly complex. This behavior is further complicated
unavoidable occurrance of indivdual equipment faliures, and the
of an overlaid protection system that can instantaneously disconnect
pieces of equipment when local overloads are detected. This talk
an overview of typical disturbance scenarios in such systems, taking
recent western US blackouts of July and August '96 as motivating
We will continue by providing an overview of the basic structure of
underlying electromechanical dynamics, and describe how these
with protective devices in a manner that may be modeled as a
event'' system. To efficiently operate a modern power grid, it is
desirable to be able to predict the dynamic response of the system
disturbances. This talk will briefly survey the current state of the
in simulation tools for this purpose, and will highlight current
efforts at UW-Madison that seek to augment these with analytic tools
assessing qualitative behavior.
15 October. Rick Jenison, UW Psychology.
Bayesian Estimation of Time-to-Arrival from Acoustic
Abstract: Much of the interest regarding an active observer
centered on precise timing of interactions with objects in the
in relation to observers, for example, a baseball player catching a
ball. An observer seeks new information by exploring the
means moving around, tracking objects in space, and avoiding
These examples certainly seem natural for the visual sense, but what
audition? Although the physical nature of optics and acoustics are
both kinds of information can be shown to sufficiently specify the
or kinematics of moving objects relative to an observer.
Theoretical work on optic information for time-to-arrival has
on a variable commonly referred to as ``tau'' that specifies the
from the optical dilation of an approaching object at any instant
An analysis similar to that for visual tau has been applied to
structure to derive an analogous acoustic tau based on detected
in sound intensity. Change in sound intensity is but one source of
for specifying motion parameters of a sound-emitting object in
in binaural and spectral structure in the forms of dynamic
interaural-intensity-differences, and Doppler shifts are also
In this talk, a dynamical system for integrating acoustic
specifies time-to-arrival (and parameters of object motion in
is presented. This model is based on Bayesian data-fusion
have been developed in the field of passive sonar. Although these
equations are nonlinear, they can be linearized sufficiently to
standard Kalman filtering techniques as recursive estimators of
variables. Theoretical lower bounds can be established using the
lower bound on the recursive estimators, which gives the minimum
that an unbiased estimator can achieve from a series of noisy
22 October. Bob Savit, Department of
of Michigan. ``Time Dependence in Complex Systems.''
Abstract: Time series generated by complex, nonlinear systems
notoriously difficult to analyze. One important problem that must be
early on, is whether the underlying dynamics driving the process is
independent. This question is related to, but not the same as, the
of stationarity. In this talk I will describe a new method for
time series from complex systems that is designed to uncover time
in the underlying dynamics. In addition to addressing the question
the underlying dynamics is time dependent or not, the approach
insight into the nature of the time dependence, if it exists. I will
applications of the method to the analysis of intracranial EEG
from patients with temporal lobe epilepsy, to a problem in
analysis, as well as to some examples of simulated data.
29 October. David Albers, UW Physics.
of Artificial Neural Networks with Random Weights.''
Abstract: In this talk I will describe a Monte Carlo study of
untrained, feedforward, neural networks with randomly chosen weights
feedback. The analysis consists of looking at the percent of the
that exhibit chaos, the distribution of largest Lyapunov exponents,
the distribution of correlation dimensions. As the systems become
complex (increasing inputs and neurons), the probability of chaos
unity. The correlation dimension is typically much smaller than the
5 November. Richard K. Belew, CSE Dept. ---
and CS Dept. --- UW (Visiting). ``Competitive Co-evolution.''
Abstract: Many of the most important design problems are
not only because there are a vast number of solutions to consider,
also because the number of TESTS for potential solutions is vast as
We analyze the ``competition dynamic'' between solutions and tests
arises in evolutionary computations: Two distinct populations of
and ``parasites'' are maintained, with increasing reproductive
of individuals in one population being at the expense of those in
The resulting search is related to the theory of PAC learning, and
heuristics are demonstrated to significantly improve the
search behavior. Game-playing applications are shown to be a very
domain for these methods, and some prelimary results applied to the
game of Go are presented.
This work is based on an upcoming dissertation by Chris Rosin,
11 November. Related Lecture. John
Center for Complex Systems, Brandeis University. ``The Role of
in Long term and Short Term Memory.''
Unusual time and place: Monday, 3:30 pm, room 341 Bardeen.
Sponsored by the Center for Neuroscience (Ken Mack, 263-9800, or
Lipton, 262-1709, for more information or contact with Dr.
12 November. Robert Meyer, UW Computer
Genetic Algorithm for Optimal Domain Decomposition.''
Abstract: The problem of ``optimally'' partitioning a given
into a specified number of pieces arises in a variety of computer
applications, from database to image analysis to partial
The general goal in all of these applications is to obtain pieces
are of nearly equal size (for load balancing in parallel computing
and, in addition, have small perimeter (in the two-dimensional case)
small surface area (in the three-dimensional case), thereby reducing
costs. This type of problem fits well into the genetic algorithm
since it can be formulated in terms of trying to determine and
good ``building blocks'' (well-shaped pieces of the domain) to
good overall solution. We present a genetic algorithm that
existing approaches to domain decomposition because it makes
use of this high-level building block information.
15 November. Related Lecture. Stuart
Circuitry of Memory and Memory Loss: Findings from Humans and
Unusual time and place: Friday, 12 noon in room 113
A University Lecture sponsored by the Psychology Department and
by the Primate Center and the Department of Psychiatry. ``Dr. Zola
internationally renowned researcher on neural mechanisms of memory
and memory loss, whose work spans both animal models and humans,
a variety of manipulative and imaging methodologies.'' Contact for
Craig Berridge, Psychology Dept.
15 November. Related Lecture. Josh
UW Math. ``Sequential Recall.''
Abstract: I'll discuss a simple two-layer neural network
has sparse forward, lateral, and feedback connections. Simulations
an ability for quick recall of a sequence of overlapping inputs,
an initial prompt--inputs learned in an unsupervised way. The
are not based on iteration to a limit. The model suggests roles for
counterparts, such as modifiable and non-modifiable channels.
19 November. Paul Terry, UW Physics.
Transport: From Fusion Reactors to the Ozone Hole.''
Abstract: There is no universal theory of turbulence, given
lack of universality in the dynamical behavior of different systems.
a recently discovered phenomenon runs counter to this trend and
to operate in essentially the same fashion in systems ranging from
plasmas to the earth's middle atmosphere. This phenomenon,
of turbulence and turbulent mixing by sheared flow, has been
removing turbulent transport in fusion devices. It may also apply to
barriers in the stratosphere, confinement of salinity and heat in
vortical ocean currents, and intermittency in 2D Navier-Stokes
This phenomenon will be described heuristically and its application
some of the above problems will be discussed.
26 November. George E. Hrabovsky, UW
Chaos in Accretion Disks.''
Abstract: This talk will discuss transient chaos in accretion
(disks of matter which spiral in to a source of intense gravitation
as black holes and neutron stars). A review of topics involving
maps, transient chaos, diffusion, and accretion will be a part of
26 November. Related Lecture.
UW Computer Sciences. ``Quantifying the Complexity of Superscalar
Unusual Time and Place: 4pm, room 1325 Computer Sciences
Abstract: This talk consists of two parts. The first part
our attempt at quantifying the complexity of superscalar
a generic superscalar pipeline is defined. Then, the specific
register renaming, window wakeup and selection logic, and operand
are analyzed. Performance (delay) results and trends are expressed
of issue width and window size. Our analysis indicates that window
and operand bypass logic are likely to be the most critical in the
The second part of the talk describes a microarchitecture that
window logic. This dependence-based microarchitecture puts
into multiple queues, and issues them from the queues in strict
Simulation shows little slowdown as compared with a completely
issue window, when performance is measured in clock cycles.
because only instructions at FIFO heads need to be awakened and
issue logic is simplified and the clock cycle is faster --
overall performance is improved. Also, the proposed
by grouping dependent instructions together, helps minimize the
degradation due to slow bypasses in future wide-issue machines.
3 December. Virginia Young, UW School of
an Expert System from Linguistic Rules--A Fuzzy Logic Approach.''
Abstract: Fuzzy logic was developed in the 1970's to provide
to account for the vagueness inherent in linguistic rules. I will
a brief background into fuzzy sets themselves and will describe how
can use fuzzy logic to create an expert system by starting with
rules. I will illustrate my method with a simple hypothetical
10 December. Christopher Kribs, UW Math. ``A
STD Model with Recruitment and Activity Levels.''
Abstract: In this talk I will present a brief overview of
systems that have been used to model the spread of a disease within
and then discuss a particular model I have developed which
division of the population both by gender and by contact rate (here
as sexual activity levels), separations which normally have not been
simultaneously because of the inherent complexity of the model(s).
of the model yields results which differ from those of simpler
in particular, the coexistence of two stable equilibria, so that
stability does not imply global stability. The physical assumptions
the model are based on studies of sexually transmitted diseases with
recovery (e.g., gonorrhea). My emphasis will be on results and their
rather than their derivations.
Up to the Chaos and Complex Systems Seminar
Last change worth mentioning Mon Nov 25 10:46:05 1996