This book is an outgrowth of courses given by me for graduate students at York University in the past ten years. The actual writing of the book in this form was carried out at York University, Peking University, the Academia Sinica in Beijing, the University of California at Irvine, Osaka University, and the University of Delaware. The idea of writing this book was ?rst conceived in the summer of 1989, and the protracted period of gestation was due to my daily duties as a professor at York University. I would like to thank Professor K. C. Chang, of Peking University; Professor Shujie Li, of...

In this edition of An Introduction to Pseudo-Differential Operators, a chapter on the interchange of order of differentiation and integration is added at the beginning, and a chapter on weak solutions of pseudo-differential equations is added at the end. Several chapters are provided with additional exercises.