1.1. What This Book is About This book is a study of - subrecursive programming systems, - efficiency/program-size trade-offs between such systems, and - how these systems can serve as tools in complexity theory. Section 1.1 states our basic themes, and Sections 1.2 and 1.3 give a general outline of the book. Our first task is to explain what subrecursive programming systems are and why they are of interest. 1.1.1. Subrecursive Programming Systems...