ABSTRACT
The chapter addresses various structured models for knowledge representation and reasoning. It starts with semantic nets and provides in detail its scope in reasoning with monotonic, non-monotonic and default knowledge bases. The principles of defeasible reasoning by semantic nets have been introduced. The concept of partitioned semantic nets to represent complex knowledge including quantifiers has been illustrated with examples. Among the other structured approaches special emphasis has been given to frames. The principles of single and multiple inheritance have been elucidated for frame structures. The rest of the chapter includes discussions on conceptual dependency graphs, scripts and Petri nets.
