Signals and Boundaries: Building Blocks for Complex Adaptive Systems

308 Pages·2012·4.06 MB·English

by  John H. Holland

Signals and Boundaries
Signals and Boundaries
Building Blocks for Complex Adaptive Systems
John H. Holland
The MIT Press
Cambridge, Massachusetts
London, England
© 2 012 M assachusetts Institute of Technology
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Set in Sabon by Toppan Best-set Premedia Limited. Printed and bound
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Library of Congress Cataloging-in-Publication Data
Holland, John H. (John Henry), 1929–
Signals and boundaries : building blocks for complex adaptive systems
/ John H. Holland.
p. cm.
Includes bibliographical references and index.
ISBN 978-0-262-01783-1 (hardcover : alk. paper)
1. Adaptive control systems. 2. Adaptation (Biology)— Mathematical
models. 3. Signals and signaling— Mathematical models. I. Title.
TJ217.H644 2012
003 — dc23
2 011052776
10 9 8 7 6 5 4 3 2 1
Contents
Preface vii
1 The Roles of Signals and Boundaries 1
2 Theory and Models: General Principles 35
3 Agents and Signal Processing 57
4 Networks and Flows 85
5 Adaptation 99
6 Recombination and Reproduction 117
7 Urn Models of Boundaries 131
8 Boundary Hierarchies 145
9 The Evolution of Niches— A First Look 159
10 Language: Grammars and Niches 181
11 Grammars as Finitely Generated Systems 205
12 An Overarching Signal/Boundary Framework 217
13 A Dynamic Generated System Model of Ontogeny 229
vi Contents
14 A Complete Dynamic Generated System for Signal/
Boundary Studies 245
15 Mathematical Models of Generated Structures 265
16 A Short Version of the Whole 281
References 297
Index 303
Preface
Many of the ideas in this book grew out of interactions at the
Santa Fe Institute and at the University of Michigan’ s Center for
the Study of Complex Systems. Equally important was Bill (S-Y)
Wang ’ s re-awakening of my interest in language acquisition and
evolution.
In the early 1960s, Bill and I worked together at the Univer-
sity of Michigan, designing the first courses for the Communica-
tion Sciences Program (later the Department of Computer and
Communication Sciences). After Bill left Michigan for a distin-
guished career at U.C. Berkeley, we were out of contact for
almost 40 years, though I was well aware of Bill ’ s research. One
day, a few years ago, I received an email from Bill (then at the
City University of Hong Kong after retiring from Berkeley) invit-
ing me to come to City U. to explore ways in which our ideas,
combined, might provide a new approach to language. There
followed, in short order, a whole series of interactions based on
extended meetings in Hong Kong and working groups at the
Santa Fe Institute.
It was through Bill that I met Professor Helena Hong Gao and
became aware of her remarkable work on children’ s acquisition
viii Preface
of their first action words. Helena is fluent in Chinese, Swedish,
and English, so she was able to compare acquisition of action
words in those three languages. She discovered the striking fact
that in all three languages children acquired their first action
words only after they could do the actions those words named.
The link between gesture and speech was unmistakable. Through
continued interactions, Helena and I began to explore what
pre-primate abilities might lead to the increasing levels of con-
sciousness involved in language acquisition.
A later workshop at the Santa Fe Institute, followed by work-
shops and meetings at the University of Michigan, led to a
manifesto by a group of well-known linguists proclaiming that
“ language is a complex adaptive system.” Because I had been
exploring the notion of niche in ecosystems, along with the
effects of boundaries in biological cells, these interactions drove
me to consider the combined effects of idiolects, dialects, and
the like, in providing “ boundaries ” ( “ them ” and “ us ” ) between
speakers. It was natural to jump from these considerations to
looking much more closely at the effects of signals and boundar-
ies in all complex adaptive systems. This book is the result.
If you had asked me when I was 60 if I would still be actively
teaching at 80, I would have said “ Absolutely not. ” But here I
am, at 83, still teaching at the University of Michigan, and
enjoying it. It is not through necessity, but because of the huge
benefits of contacts with new students full of curiosity and
original insights. And I am extremely fortunate to still have
active interactions with colleagues all over the world. It is indeed
a complex, intriguing planet!
1 The Roles of Signals and Boundaries
Ecosystems, governments, biological cells, markets, and complex
adaptive systems in general are characterized by intricate hierarchal
arrangements of boundaries and signals.
Ecosystems, for example, have highly diverse niches, with smells
and visual patterns as signals. Governments have departmental hier-
archies, with memoranda as signals. Biological cells have a wealth
of membranes, with proteins as signals. Markets have traders and
specialists who use buy and sell orders as signals. And so it is with
other complex adaptive systems. Despite a wealth of data and descrip-
tions concerning different complex adaptive systems, we still know
little about how to steer these systems. It is the stance of this book
that widely applicable answers to questions about steering complex
adaptive systems can be attained only by studying the origin and the
coevolution of signal/boundary hierarchies, much as the intricacies of
ecosystems can be understood only by studying the origin and the
coevolution of species.
Though the book makes substantial use of data and examples, its
objective is not to produce models that make specific predictions from
data. Instead, its objective is to examine mechanisms that underpin
the development of hierarchies of signals and boundaries in complex
2 Chapter 1
adaptive systems. The critical role of mechanisms is nicely illustrated
by Jacob Bjerknes ’ discovery of fronts as a weather-generating mecha-
nism. Before Bjerknes, weather was predicted by statistical trend
analysis based on snapshots of current conditions. (For example, the
prediction “ tomorrow ’ s weather will be like today’ s ” is right about 60
percent of the time.) Bjerknes’ discovery suggested where to look
for new relevant data, and how to make predictions conditional on
those data. Similarly, the objective here is to find mechanisms that
suggest where to look for new data that explain the development of
signal/boundary hierarchies. The book’ s ultimate goal is to tie these
mechanisms into a single overarching framework that suggests ways
to steer complex adaptive systems by modifying signal/boundary
hierarchies.
Adaptive agent Network of
adaptive agents
[Adaptive agents
compete and adapt
to each other.] The aggregate behavior
influences agent behavior
as well as vice-versa.
Because of conditional
interactions, the behavior
of the aggregate is not Aggregate agent
simply the sum of the
[Aggregate behavior of component
agent actions.
agents generates behavior of the
aggregate agent.]
Figure 1.1
Complex adaptive systems.
The Roles of Signals and Boundaries 3
1.1 Prologue
Consider three events:
• A monkey gives the “ eagle-warning ” cry, though no eagle is
present, watching her companions depart the forest canopy
while she remains to feast on the tasty green shoots.
• India and Pakistan contest the dominion of Kashmir, a vale
of mountainous terrain that separates them.
• Witches, singing “ Double, double, toil and trouble; Fire burn
and cauldron bubble, ” watch over a vat full of exotic organic
compounds.
Though these three events seem to have little in common, there
is a thread that connects them: in each case, signals, boundaries,
and the interactions between them play a critical role.
Consider the monkey’ s cry. Clearly it is a signal, but what are
the boundaries? We must look more closely at the monkey ’ s
environment to see the relevant boundaries. This monkey (a
vervet) lives in a savannah forest, eating young shoots that grow
high in the trees. The savannah forest consists of a variety of
resources and nutrients, ranging from leaves on the trees and
insects in the bark to the monkeys themselves. We say that the
vervets live in a niche that consists of the things they eat and
the things that eat them. The niche, then, is made up of physical
and virtual boundaries that determine the limits of these inter-
actions. By using well-established signals in a deceptive way, the
monkey gains a larger share of the resources in its niche. The
invisible boundaries that define niches are a complex topic, still
only partly understood. And there is another mystery here.
Warning cries are pervasive in the animal world, but the animal
issuing the warning cry immediately calls the predator ’ s