JOURNAL OF PURE AND APPLIED ALGEBRA AS ELSEVIER Journal of Pure and Applied Algebra 175 (2002) v-vi www.elsevier.com/locate/jpaa Special Volume celebrating the 70th birthday of Professor Max Kelly CONTENTS A. Carboni, G. Janelidze, R. Street Foreword J. Adamek, F. Borceux, S. Lack, J. Rosicky A classification of accessible categories D. Bourn, M. Gran Central extensions in semi-abelian categories T. Brzezinski, S. Caenepeel, G. Militaru Doi-—Koppinen modules for quantum groupoids M. Bunge, J. Funk, M. Jibladze, T. Streicher The Michael completion of a topos spread C. Centazzo, R.J. Wood An extension of the regular completion K.A. Hardie, K.H. Kamps, H.J. Marcum The Toda bracket in the homotopy category of a track bicategory P. Hines A short note on coherence and self-similarity M. Hyland, J. Power Pseudo-commutative monads and pseudo-closed 2-categories G. Janelidze, M. Sobral Finite preorders and Topological descent | A. Joyal Quasi-categories and Kan complexes S. Lack Codescent objects and coherence S. Lack, R. Street The formal theory of monads II F.W. Lawvere Categorical algebra for continuum micro physics C.J. Mulvey, J.W. Pelletier On the quantisation of spaces R. Rosebrugh, R.J. Wood Distributive laws and factorization J. Rosicky, W. Tholen Lax factorization algebras E.M. Vitale A Picard-Brauer exact sequence of categorical groups Author Index Volume 175