Preface ....................................................................................................... vii
1 Introduction ...................................................................................... !
1.1 Introduction .......................................................................... 1
1.2 The Blackboard Metaphor ................................................... 3
1.3 Comparison with Production Rules ...................................... 9
2 The Blackboard Architecture: A Definition
and Example Systems ................................................................... 15
2.1 Introduction ....................................................................... 15
2.2 The Blackboard Architecture: A Definition .................... .17
2.3 The Evolution of the Architecture .................................... 32
3 Control .......................................................................................... 52
3.1 Introduction ........................................................................ 52
3.2 The Focus of Attention Problem ....................................... 55
3.3 Strategies and High-Level Control .................................... 78
3.4 Opportunism ...................................................................... 83
3.5 Example Schedulers .......................................................... 88
3.6 Summary ......................................................................... 101
4 Building Blackboard Systems .................................................... 103
4.1 Introduction ..................................................................... 103
4.2 Methodology Outline ...................................................... 104
4.3 A Method for Building Blackboard Systems .................. 108
4.4 A Review ......................................................................... 134
5 WordSys-Using the Methodology ............................................ 136
5.1 Introduction ...................................................................... 136
5.2 The Problem .................................................................... 137
5.3 WordSys Design .............................................................. 140
5.4 Knowledge Sources ......................................................... 149
5.5 Control ............................................................................. 156
5.6 Representations and External Databases ......................... 162
5.7 NBB Overview ................................................................ 169
5.8 Conclusions ...................................................................... 177
6 Conclusions ................................................................................. 179
6.1 Introduction ...................................................................... 179
6.2 General Review .............................................................. .179
6.3 Future Developments ....................................................... 181
6.4 Postscript ......................................................................... 189
Appendix 1: A Blackboard System Interpreter Design ........... .194
A.1 Introduction ..................................................................... 194
A.2 General Decisions ........................................................... 195
A.3 Interpreter Design ........................................................... 200
A.4 Further Enhancements ..................................................... 228
Appendix 2: Glossary of Terms ................................................ 229
References ................................................................................... 232
Author Index ............................................................................... 237
Subject Index .............................................................................. 239