This work is devoted to a study of various relations between non-classical logics and fuzzy sets. This volume is aimed at all those who are interested in a deeper understanding of the mathematical foundations of fuzzy set theory, particularly in intuitionistic logic, Lukasiewicz logic, monoidal logic, fuzzy logic and topos-like categories. The tutorial nature of the longer chapters, the comprehensive bibliography and index should make it suitable as a valuable and important reference for graduate students as well as research workers in the field of non-classical logics. The book is arranged in three parts: part A presents the most recent developments in the theory of Heyting algebras, MV-algebras, quantales and GL-monoids; part B gives a coherent and current account of topos-like categories for fuzzy set theory based on Heyting algebra valued sets, quantal sets of M-valued sets; part C addresses general aspects of non-classical logics including epistemological problems as well as recursive properties of fuzzy logic.