Earth Is Room Enough

DEDICATION:

To Those Admirable and Amiable Gendlemen Who First Occasioned the Publication of These Stories: Anthony Boucher . . . Howard Browne . . . John Campbell . . . Horace Gold . . . Robert Lowndes . . . Leo Margulies . . . Ray Palmer . . . James Quinn . . . Larry Shaw . . . Russ Winterbotham

THIS BOOK CONTAINS THE COMPLETE TEXT OF THE ORIGINAL HARDCOVER EDITION.

Copyright © 1957 by Isaac Asimov

CONTENTS

The Dead Past
The Foundation of S.F. Success
Franchise
Gimmicks Three
Kid Stuff
The Watery Place
Living Space
The Message
Satisfaction Guaranteed
Hell-Fire
The Last Trump
The Fun They Had
Jokester
The Immortal Bard
Someday
The Author’s Ordeal
Dreaming Is a Private Thing


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Electronic Commerce The Strategic Perspective

Table of Contents
Preface.........................................................................................................................................................4
1. Electronic commerce: An introduction...............................................................5
Electronic commerce defined......................................................................................................................5
Who should use the Internet?.....................................................................................................................5
Why use the Internet?.................................................................................................................................6
Disintermediation.......................................................................................................................................8
Key themes addressed.................................................................................................................................9
2. Electronic commerce technology ................................................................ ......16
Internet technology.................................................................................................................................... 6 1
Infrastructure.............................................................................................................................................17
Electronic publishing.................................................................................................................................18
Electronic commerce topologies...............................................................................................................19
Security......................................................................................................................................................22
Electronic money..................................................................................................................................... .26 .
Secure electronic transactions..................................................................................................................28
3. Web strategy: Attracting and retaining visitors.................................................32
Types of attractors ....................................................................................................................................33
Attractiveness factors................................................................................................................................38
Sustainable attractiveness ........................................................................................................................ 0 4
Strategies for attractors ............................................................................................................................41
Conclusion ................................................................................................................................................43
4. Promotion: Integrated Web communications...................................................45
Internet technology for supporting marketing ........................................................................................45
Integrated Internet Marketing..................................................................................................................46
5. Promotion & purchase: Measuring effectiveness..............................................52
The Internet and the World Wide Web....................................................................................................52
An electronic trade show and a virtual flea market..................................................................................52
The role of the Web in the marketing communication mix.....................................................................54
Web marketing communication: a conceptual framework......................................................................56
6. Distribution............................................................................................ ..........63
What is the purpose of a distribution strategy?.......................................................................................63
What does technology do?........................................................................................................................64
The Internet distribution matrix...............................................................................................................65
The effects of technology on distribution channels..................................................................................66
Some long-term effects ............................................................................................................................. 0 7
7. Service.................................................................... ..........................................74
What makes services different?................................................................................................................74
Cyberservice.................................................................................................................................... ..........75
.
8. Pricing.............................................................................................................. 82
Web pricing and the dynamics of markets...............................................................................................82
Flattening the pyramid and narrowing the scope of marketing..............................................................85
Migrating up the pyramid and more effective marketing .......................................................................87
9. Post-Modernism and the Web: Societal effects.................................................92
What is modernism?.................................................................................................................................92
And Post-Modernism?..............................................................................................................................93
Fragmentation...........................................................................................................................................94
Dedifferentiation ......................................................................................................................................94
Hyperreality ..............................................................................................................................................95
Time and space..........................................................................................................................................96
Paradox, reflexivity, and pastiche.............................................................................................................97
Anti-foundationalism ...............................................................................................................................98


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Distributed Search by Constrained Agents

Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Constraints Satisfaction Problems - CSPs . . . . . . . . . . . . . . . . . . 7
2.1 Defining CSPs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 CSP Algorithms and Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3 Behavior of CSP solving algorithms . . . . . . . . . . . . . . . . . . . . . . . . 13
3 Constraints Optimization Problems - COPs . . . . . . . . . . . . . . . . 19
3.1 Branch and Bound (BnB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.2 Branch and Bound + Arc-Consistency (BnB-AC) . . . . . . . . . . . . 23
3.3 Branch and Bound + AC* (BnB-AC*) . . . . . . . . . . . . . . . . . . . . . 24
3.4 Phase Transition in MaxCSPs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4 Distributed Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.1 Distributed search algorithms on DisCSPs . . . . . . . . . . . . . . . . . . 30
4.2 Introducing Asynchronous Backtracking . . . . . . . . . . . . . . . . . . . . 33
5 Asynchronous Backtracking (ABT) . . . . . . . . . . . . . . . . . . . . . . . . 37
5.1 A Complete 4-Queens Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.2 The ABT Algorithm - Polynomial Storage . . . . . . . . . . . . . . . . . . 43
5.3 Correctness of ABT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.4 Improving Performance of ABT . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
6 Asynchronous Forward-Checking . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6.1 AF C - Algorithm Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.2 Correctness of AFC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
6.3 Improved Backtrack Method for AFC . . . . . . . . . . . . . . . . . . . . . . 61
7 Concurrent Dynamic Backtracking . . . . . . . . . . . . . . . . . . . . . . . . 63
7.1 4-Queens with Concurrent Search . . . . . . . . . . . . . . . . . . . . . . . . . . 65
7.2 The ConcBT Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
7.2.1 A splitting of search space example . . . . . . . . . . . . . . . . . . 72
7.3 Concurrent Dynamic Backtracking . . . . . . . . . . . . . . . . . . . . . . . . . 75
7.4 Correctness of Concurrent Search . . . . . . . . . . . . . . . . . . . . . . . . . . 79
8 Distributed Ordering Heuristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
8.1 Ordering heuristics for Synchronous Backjumping . . . . . . . . . . . 85
8.1.1 Heuristics with no additional messages . . . . . . . . . . . . . . . 85
8.1.2 Heuristics with additional network overhead . . . . . . . . . . 86
8.2 Ordering heuristics for AF C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
9 Asynchronous Ordering Heuristics . . . . . . . . . . . . . . . . . . . . . . . . . 89
9.1 Specific Asynchronous Heuristics . . . . . . . . . . . . . . . . . . . . . . . . . . 89
9.2 Dynamically ordered ABT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
9.3 Correctness of ABT _DO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
9.4 A new class of asynchronous heuristics . . . . . . . . . . . . . . . . . . . . . 97
9.5 Correctness of Retroactive ABT _DO . . . . . . . . . . . . . . . . . . . . . . 102
10 Performance measures for distributed search . . . . . . . . . . . . . . 105
10.1 A Simple Example with Naive Methods . . . . . . . . . . . . . . . . . . . . 107
10.2 Dividing concurrent search into rounds . . . . . . . . . . . . . . . . . . . . 108
10.3 A More Complex Example for Computing NCCCs . . . . . . . . . . . 110
10.4 A Model for Nonconcurrent Constraints Checks . . . . . . . . . . . . . 111
10.5 The Cumulative Cost Algorithm (CCA) . . . . . . . . . . . . . . . . . . . . 113
10.6 Realization of the Model by the CCA Algorithm . . . . . . . . . . . . 115
11 Experimental Evaluation of DisCSP Algorithms . . . . . . . . . . 121
11.1 Comparing Different Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
11.1.1 Asynchronous forward-checking vs. ABT . . . . . . . . . . . . . 122
11.1.2 Experimental evaluation of ConcDB . . . . . . . . . . . . . . . . 123
11.2 Empirical Evaluation of Heuristic Ordering . . . . . . . . . . . . . . . . . 125
11.2.1 Evaluation of synchronous ordering heuristics . . . . . . . . . 126
11.2.2 Evaluation of dynamically ordered ABT . . . . . . . . . . . . . . 128
11.2.3 Retroactive ordering for ABT . . . . . . . . . . . . . . . . . . . . . . . 133
12 The Impact of Communication - Message Delays . . . . . . . . . . 137
12.1 Simulating Delayed Messages on DisCSPs . . . . . . . . . . . . . . . . . . 139
12.1.1 Adjusting the measuring method for dynamic ordering 140
12.2 Validity of AM DS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
13 Message Delays and DisCSP Search Algorithms . . . . . . . . . . . 143
13.1 The Impact of Message Delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
13.2 A summary of the Impact of Message Delays . . . . . . . . . . . . . . . 154
13.3 Message Delays and Dynamic Ordering . . . . . . . . . . . . . . . . . . . . . 156
14 Distributed Constraint Optimization Problems (DisCOPs) 159
14.1 Pseudo-trees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
14.2 Synchronous Branch and Bound (SBB) . . . . . . . . . . . . . . . . . . . . . 161
14.3 Distributed Pseudo-tree Optimization (DPOP) . . . . . . . . . . . . . . 162
14.4 Optimal Asynchronous Partial Overlay (OptAPO) . . . . . . . . . . . 164
15 Asynchronous Optimization for DisCOPs . . . . . . . . . . . . . . . . . 169
15.1 Lower and Upper Bounds in ADOP T . . . . . . . . . . . . . . . . . . . . . . 170
15.1.1 Computing lower and upper bounds . . . . . . . . . . . . . . . . . 171
15.2 Assigning Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
15.3 The Threshold Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
15.4 ADOP T - Summary and Termination . . . . . . . . . . . . . . . . . . . . . . 176
15.5 Special (and Surprising) Features of ADOP T . . . . . . . . . . . . . . . 178
15.5.1 Updating context from lower priority agents . . . . . . . . . . 179
15.5.2 Pseudo-trees and concurrency of computation . . . . . . . . . 180
15.5.3 Network load of ADOP T . . . . . . . . . . . . . . . . . . . . . . . . . . 182
16 Asynchronous Forward-Bounding . . . . . . . . . . . . . . . . . . . . . . . . . . 183
16.1 AFB - Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
16.2 Lower Bound Estimation for the Cost Increment . . . . . . . . . . . . 184
16.3 AFB - Algorithm Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
16.4 The Time-Stamp Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
16.5 AFB - Proof of Correctness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
16.6 Concurrency in AFB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
17 Extending AFB - BackJumping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
17.1 Adding Value Ordering Heuristics . . . . . . . . . . . . . . . . . . . . . . . . . 194
17.2 Backjumping - Key Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
17.3 A Backjumping Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
17.4 The AFB-BJ Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
17.5 AFB-BJ - Proof of Correctness . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
18 Empirical Evaluation of DisCOP algorithms . . . . . . . . . . . . . . . 203
18.1 Empirical Evaluation of AFB and AFB-BJ . . . . . . . . . . . . . . . . . 204
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215


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Developing Intelligent Agent Systems A Practical Guide

Contents
Foreword from the Series Editor ix
Preface xi
Acknowledgement xiii
1 Agents and Multi-Agent Systems 1
1.1 What is an Intelligent Agent? . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Why are Agents Useful? . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Concepts for Building Agents 7
2.1 Situated Agents: Actions and Percepts . . . . . . . . . . . . . . . . . . . 7
2.2 Proactive and Reactive Agents: Goals and Events . . . . . . . . . . . . 8
2.3 Challenging Agent Environments: Plans and Beliefs . . . . . . . . . . . 10
2.4 Social Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.5 Agent Execution Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.5.1 Choice of Plan to Execute . . . . . . . . . . . . . . . . . . . . . 14
2.5.2 Many Ways to Achieve a Goal . . . . . . . . . . . . . . . . . . 16
2.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3 Overview of the Prometheus Methodology 21
3.1 Why a New Methodology? . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2 Prometheus: A Brief Overview . . . . . . . . . . . . . . . . . . . . . . 23
3.2.1 System Specification . . . . . . . . . . . . . . . . . . . . . . . . 24
3.2.2 Architectural Design . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2.3 Detailed Design . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.3 Guidelines for Using Prometheus . . . . . . . . . . . . . . . . . . . . . 27
3.4 Agent-Oriented Methodologies . . . . . . . . . . . . . . . . . . . . . . . 29
4 System Specification 33
4.1 Goal Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.1.1 Identify Initial Goals . . . . . . . . . . . . . . . . . . . . . . . . 35
4.1.2 Goal Refinement . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2 Functionalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.3 Scenario Development . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.3.1 Goal Step Details . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.3.2 Capturing Alternative Scenarios . . . . . . . . . . . . . . . . . . 46
4.4 Interface Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.4.1 Percepts and Actions . . . . . . . . . . . . . . . . . . . . . . . . 48
4.4.2 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.5 Checking for Completeness and Consistency . . . . . . . . . . . . . . . 51
5 Architectural Design: Specifying the Agent Types 53
5.1 Deciding on the Agent Types . . . . . . . . . . . . . . . . . . . . . . . 56
5.2 Grouping Functionalities . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.3 Review Agent Coupling – Acquaintance Diagrams . . . . . . . . . . . . 63
5.4 Develop Agent Descriptors . . . . . . . . . . . . . . . . . . . . . . . . . 65
6 Architectural Design: Specifying the Interactions 67
6.1 Interaction Diagrams from Scenarios . . . . . . . . . . . . . . . . . . . 68
6.2 Interaction Protocols from Interaction Diagrams . . . . . . . . . . . . . 74
6.3 Develop Protocol and Message Descriptors . . . . . . . . . . . . . . . . 77
7 Finalizing the Architectural Design 81
7.1 Overall System Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 82
7.2 Identifying Boundaries of the Agent System . . . . . . . . . . . . . . . 82
7.3 Describing Percepts and Actions . . . . . . . . . . . . . . . . . . . . . . 84
7.4 Defining Shared Data Objects . . . . . . . . . . . . . . . . . . . . . . . 88
7.5 System Overview Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 91
7.6 Checking for Completeness and Consistency . . . . . . . . . . . . . . . 94
7.6.1 Consistency between Agents and Functionalities . . . . . . . . . 95
7.6.2 Consistency between Interaction Diagrams, Scenarios
and Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7.6.3 Consistency of Communication Specifications . . . . . . . . . . 96
7.6.4 Consistency between Descriptors and the System
Overview Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 97
8 Detailed Design: Agents, Capabilities and Processes 99
8.1 Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
8.2 Agent Overview Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . 102
8.3 Process Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
8.4 Develop Capability and Process Descriptors . . . . . . . . . . . . . . . 106
9 Detailed Design: Capabilities, Plans and Events 109
9.1 Capability Overview Diagrams . . . . . . . . . . . . . . . . . . . . . . . 110
9.2 Sub-tasks and Alternative Plans . . . . . . . . . . . . . . . . . . . . . . 112
9.2.1 Identifying Context Conditions . . . . . . . . . . . . . . . . . . 113
9.2.2 Coverage and Overlap . . . . . . . . . . . . . . . . . . . . . . . 115
9.3 Events and Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
9.4 Action and Percept Detailed Design . . . . . . . . . . . . . . . . . . . . 117
9.5 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
9.6 Develop and Refine Descriptors . . . . . . . . . . . . . . . . . . . . . . 118
9.7 Checking for Completeness and Consistency . . . . . . . . . . . . . . . 119
9.7.1 Agent Completeness . . . . . . . . . . . . . . . . . . . . . . . . 120
9.7.2 Missing or Redundant Items . . . . . . . . . . . . . . . . . . . . 120
9.7.3 Consistency between Artifacts . . . . . . . . . . . . . . . . . . . 121
9.7.4 Impotant Scenarios . . . . . . . . . . . . . . . . . . . . . . . . 123
10 Implementing Agent Systems 125
10.1 Agent Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
10.2 JACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
10.3 Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
10.3.1 Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
10.3.2 Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
10.3.3 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
10.3.4 Messages/Events . . . . . . . . . . . . . . . . . . . . . . . . . . 134
10.3.5 Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
10.4 Automatic Generation of Skeleton Code . . . . . . . . . . . . . . . . . . 138
A Electronic Bookstore 139
B Descriptor Forms 199
C The AUML Notation 205
Bibliography 215
Index 221

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Designing Visual Interfaces

Kevin Mullet, Macromedia.Com
Darrell Sano, Sun Microsystems Press
ISBN-10: 0133033899
ISBN-13: 9780133033892
Publisher: Prentice Hall
Copyright: 1995
Format: Paper; 304 pp
Published: 12/05/1994


Table of Contents



Foreword, Jakob Nielson.


Introduction.


Elegance and Simplicity.


Scale, Contrast, and Proportion.


Organization and Visual Structure.


Module and Programme.


Image and Representation.


So What About Style?


Conclusion.


Further Information.


About the Authors.


Bibliography.

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The Early Asimov or Eleven Years of Trying

Stories Included:

The Callistan Menace
Ring Around the Sun
The Magnificent Possession
Trends
The Weapon Too Dreadful to Use
Black Friar of the Flame
Half-Breed
The Secret Sense
Homo Sol
Half-Breeds on Venus
The Imaginary
Heredity
History
Christmas On Ganymede
The Little Man on the Subway
The Hazing


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