Identifying new material

The vast majority of results in this book have never appeared in published form before. A few were however included—implicitly or explicitly—in publications of mine from the early 1980s (see page 881). Whenever I am aware of antecedents to major material in the main text I have indicated this in the notes. Within the notes themselves, results that are given without historical discussion and without statements such as "it is known that" are generally new to this book. Researchers seeking further information should consult the website for the book.