Approved:

To my family and friends who made my graduate school years enjoyable. iii Acknowledgements Special thanks go to my friend and advisor, Professor Zvi Kedem. I still re-member the rst time he called me into his oÆce and asked \what do you want, and what are you planning to do? " That was over ve years ago. Since that day I have learned much from him, and his continual guidance and support has made this thesis possible. Last week, in helping me to make an employment decision, he called me into his oÆce and asked: \what do you want and what are you planning to do? " I look forward to our continuing friendship. I am also grateful to my friend Professor Partha Dasgupta whose insights were the foundation of my work. His thoughts and suggestions have greatly improved the content and clarity of this dissertation. In addition to Zvi and Partha, I am deeply indebted to my other committee members, Emerald Chung, Krishna Palem and Vijay Karamcheti, for giving me many good suggestions on how to present, position, and think about my work. I raise my glass in thanks to some special people who made my graduate school years enjoyable. Of these numerous friends, I can only mention a few, although I salute them all. Three cheers to Fangzhe Chang, Raoul Daruwala, Ian Jermyn