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
