Acknowledqments Therefore will I give thanks to thee PSALM 18:50 First thanks go to my home institution,the Weizmann Institute of Science,for providing the ideal supportive and encouraging environment for this kind of endeavor. My deepest gratitude goes to Yishai Feldman(who was my very first PhD student many years ago,and)who graciously agreed to join me in the preparation of this, the third,edition.I am grateful for the time,energy,and talent he put into this project.There is absolutely no way the revision would have been carried out without him. Parts of the original edition of the book were written while I was visiting Digital Equipment Corporation's Systems Research Center in Palo Alto,California,in the summer of 1985 and Carnegie-Mellon University's Computer Science Department for the 1986/7 academic year.I would like to express my deepest gratitude for these opportunities to work on the book undisturbed.Later visits to Cornell University, Bell Labs,NASA,and Lucent Technologies provided time to work on some of the revisions for the second and third editions. The late T.Yuval,Managing Editor of the Broadcast University programs on the Israeli radio channel "Galei Zahal,"deserves special thanks for convincing me to prepare the 1983-4 lecture series out of which the original version of this book later grew. I am indebted to my colleagues at the Weizmann Institute,A.Pnueli,A.Shamir, and S.Ullman,for discussions related to the material appearing herein.It is amazing how one's whole approach can benefit from being surrounded by researchers of such caliber. A very special thanks goes to R.Rosner,who co-authored the exercises and solutions,which first appeared as part of the second edition,and to Eyal Mashiah for his help in preparing the index for the present edition. I am grateful to the many people who read parts of the original 1987 manuscript or later editions,identified errors,made bibliographic suggestions,or provided helpfulP1: GIG PE002-FM PE002-Harel PE002-Harel-FM-v1.cls March 19, 2004 19:35 Acknowledgments Therefore will I give thanks to thee PSALM 18: 50 First thanks go to my home institution, the Weizmann Institute of Science, for providing the ideal supportive and encouraging environment for this kind of endeavor. My deepest gratitude goes to Yishai Feldman (who was my very first PhD student many years ago, and) who graciously agreed to join me in the preparation of this, the third, edition. I am grateful for the time, energy, and talent he put into this project. There is absolutely no way the revision would have been carried out without him. Parts of the original edition of the book were written while I was visiting Digital Equipment Corporation’s Systems Research Center in Palo Alto, California, in the summer of 1985 and Carnegie-Mellon University’s Computer Science Department for the 1986/7 academic year. I would like to express my deepest gratitude for these opportunities to work on the book undisturbed. Later visits to Cornell University, Bell Labs, NASA, and Lucent Technologies provided time to work on some of the revisions for the second and third editions. The late T. Yuval, Managing Editor of the Broadcast University programs on the Israeli radio channel “Galei Zahal,” deserves special thanks for convincing me to prepare the 1983–4 lecture series out of which the original version of this book later grew. I am indebted to my colleagues at the Weizmann Institute, A. Pnueli, A. Shamir, and S. Ullman, for discussions related to the material appearing herein. It is amazing how one’s whole approach can benefit from being surrounded by researchers of such caliber. A very special thanks goes to R. Rosner, who co-authored the exercises and solutions, which first appeared as part of the second edition, and to Eyal Mashiah for his help in preparing the index for the present edition. I am grateful to the many people who read parts of the original 1987 manuscript or later editions, identified errors, made bibliographic suggestions, or provided helpful xvii