The survey considers both adaptable and nonadaptable models. Descriptive merits and demerits of existing models are analyzed and compared. The survey is extensive, but by no means comprehensive. It is intended to identify and study important concepts and techniques that will be used in the development of the proposal in Part II. Therefore, emphasis is skewed in favor of those models that introduce important concepts or offer useful insights. Chapter 1 is devoted to Chomsky grammars; Chapter 2 surveys nonadaptable extensions of CFGs; Chapter 3 surveys adaptable grammar models.
In Part II, Chapter 4 details the design goals of the proposal and explains how the proposal addresses them. Chapter 5 formally defines the RAG model in its most general form, and Chapter 6 defines some important subclasses of RAGs. Chapter 7 compares RAGs to some of the models surveyed in Part I, and discusses areas for future research.