Abstract

This is a handbook, written by a number of authors from different research communities. Even though the subject matter of the book is reasonably unified, the divergence between their communities – firstly category theory and type theory, secondly universal algebra, and thirdly classical logic and complexity theory -- makes it difficult to get an overview; these communities are notorious for their poor relations with each other. Thus, even though it would be tempting to envisage a world in which the various chapters would be written so as to illuminate each other, and in which prospective readers would have a broad enough background to be able to appreciate all of this book, it is not the world that we live in.