This book is intended as a fairly complete presentation of what--'We
call the discretization approach to functional integrals, i.e. path
integrals defined as limits of discretized axpressions. In its main
parts it is based 0n the original work of the authors. We hope to have
provided the readers with a rather complete and up-to-date bibliography,
and we apologize to authors whose work has not been cited through
ignorance ori our part. Our main concern has been to present a for-
malism that is practical and which can be adapted to make computations
in the numerous areas where path integrals are being increasingly used.
For these reasons applications, illustrative examples, and detailed
calculations are included. The book is partially based on lectures given
by one of us (E.T.) at the Institut de Physique Theorique of the u.c.L.
(Louvain-la-Neuve). We thank Dr. M.E. Brachet (University of Paris) for
his help in the redaction of chapter 8. We are indebted to many of our
colleagues and especially to the members of the Instituut voor
Theoretische Fysica, K.U. Leuven for their interest and encouragement.
We also thank Professor Claudio Anguita, Dean of the Faculty of Physics
and Mathematics of .the University of Chile, for his constant support.
Special thanks are due to Christine Detroije and Lutgarde Dubois for
their very fine and hard work in typing the manuscript.