Categorical Preliminaries

Before embarking on the actual topic of this book, we wish to review briefly the basic notions that will be used from category theory. Many readers will be familiar with these preliminaries; they should immediately start with Chapter I, referring back to these preliminaries whenever necessary. On the other hand, these preliminaries do not present sufficiently many examples and are by no means enough to constitute a proper introduction to category theory, and the reader who lacks sufficient categorical background is advised to first read some of the relevant parts of Mac Lane’s [CWM—Categories for the Working Mathematician 1971] (or some other such text), perhaps using the following pages as a guideline.