Per Martin-Loef's work on the development of constructive type theory has been of huge significance in the fields of logic and the foundations of mathematics. It is also of broader philosophical significance, and has important applications in areas such as computing science and linguistics. This volume draws together contributions from researchers whose work builds on the theory developed by Martin-Loef over the last twenty-five years. As well as celebrating the anniversary of the birth of the subject it covers many of the diverse fields which are now influenced by type theory. It is an invaluable record of areas of current activity, but also contains contributions from N. G. de Bruijn and William Tait, both important figures in the early development of the subject. Also published for the first time is one of Per Martin-Loef's earliest papers.

Constructive topology is an important new branch of constructive mathematics and logic and this monograph is the first account of constructive topology in book form. Aimed at researchers in mathematics, philosophy, and logic, the author provides discussion of the technical development of the field and also outlines the philosophical and methodological motivations underlying the evolution of the discipline.