EDITOR'S FOREWORD TO THE SECOND EDITION xiii
since 1970. But it is perhaps worth remarking on the large extent to which the
formal structures of these theories are patterned on the methods of this book.
In preparing this edition I have added notes at the beginnings and ends of
various chapters, and footnotes; I have also updated and renumbered the refer-
ences. All my additions are set in italic type. However, I have not modified the
text itself except to correct misprints and to occasionally bring the terminology
into line with current usage.
A. A. Ranicki, Edinburgh, January 1999.