Categories for the Working Mathematician provides an array of general ideas useful in a wide variety of fields. Starting from the foundations, this book illuminates the concepts of category, functor, natural transformation, and duality. The book then turns to adjoint functors, which provide a description of universal constructions, an analysis of the representations of functors by sets of morphisms, and a means of manipulating direct and inverse limits. These categorical concepts are extensively illustrated in the remaining chapters, which include many applications of the basic existence...

J. Richard Biichi is well known for his work in mathematical logic and theoretical computer science. (He himself would have sharply objected to the qualifier "theoretical," because he more or less identified science and theory, using "theory" in a broader sense and "science" in a narrower sense than usual.) We are happy to present here this collection of his papers. I (DS)1 worked with Biichi for many years, on and off, ever since I did my Ph.D. thesis on his Sequential Calculus. His way was to travel locally, not globally: When we met we would try some specific problem, but rarely dis cussed...

A preface usually ends with appropriate expressions of thanks to the people who have helped. I would like instead to begin in that way. Most important is my gratitude to Samuel Eilenberg, Roger Lyndon, and Max Kelly, who joined me in contributing essays, and to Alfred Putnam who wrote the biography that leads off the volume. Dorothy Mac Lane helped generously with her encouragement (and of course her special source of information). Freda Davidson pitched in gallantly in helping to proofread the selected papers for typographical slips that had somehow eluded the eagle eye of Saunders Mac Lane...