My deepest gratitude is to my advisor, Dr. Don Perlis. I have been amazingly fortunate to have an advisor who gave me the freedom to explore on my own, and at the same time the guidance to recover when my steps faltered. Don taught me how to question thoughts and express ideas. His patience and support helped me overcome many crisis situations and finish this dissertation. I hope that one day I would become as good an advisor to my students as Don has been to me.
My co-advisor, Dr. Mike Anderson, has been always there to listen and give advice. I am deeply grateful to him for the long discussions that helped me sort out the technical details of my work. I am also thankful to him for encouraging the use of correct grammar and consistent notation in my writings and for carefully reading and commenting on countless revisions of this manuscript.
Dr. Jim Hendler's insightful comments and constructive criticisms at different stages of my research were thought-provoking and they helped me focus my ideas. I am grateful to him for holding me to a high research standard and enforcing strict validations for each research result, and thus teaching me how to do research.
Dr. David Kueker is one of the best teachers that I have had in my life. He sets high standards for his students and and he encourages and guides them to meet those standards. He introduced me to Mathematical Logic and his teachings inspired me to work on Chapter 5 of this dissertation. I am indebted to him for his continuous encouragement and guidance.
I am grateful to Dr. Tim Oates for his encouragement and practical advice. I am also thankful to him for reading my reports, commenting on my views and helping me understand and enrich my ideas.
I am also indebted to the members of the Active logic, Metacognitive Computation and Mind Research Group with whom I have interacted during the course of my graduate studies. Particularly, I would like to acknowledge Dr. David Traum, Dr. Ken Hennacy, Dr. Khemdut Purang, Carl Andersen, Waiyian Chong and Yoshi Okamoto for the many valuable discussions that helped me understand my research area better. I am indebted to Dr. Khemdut Purang for implementing the reasoner that much of my research is based on. I appreciate the efforts of the many undergraduate students who implemented different test domains (task-oriented systems) for testing the agent that resulted from this research; my sincere thanks to Paolo Del Mundo, Randolph Baden, Shivangi Bhatt, Amarpreet Singh, Dominique Fotso, Arash Khosh, Muhammad Ali, Luis Marti, Messay Bekele and Alexey Vedernikov for their contributions to the various domains.
I would like to acknowledge Dr. Dianne O'Leary, Dr. Michelle Hugue, Dr. John Horty, Dr. Philip Resnik and Dr. V. S. Subrahmanian for numerous discussions and lectures on related topics that helped me improve my knowledge in the area.
I am also thankful to the system staff who maintained all the machines in my lab so efficiently that I never had to worry about viruses, losing files, creating backups or installing software. I do not envy their job. I feel that they are the greatest system administrators in the world. Kudos to Brad Plecs, Geoffrey Ransom and the rest of the team!
I am also grateful to the following former or current staff at University of Maryland, for their various forms of support during my graduate study--Nancy Lindley, Felicia Chelliah, Fatima Bangura, Edna Walker, Jodie Gray, Sue Blandford, Adelaide Findlay, Brenda Chick and Heather Murray.
Many friends have helped me stay sane through these difficult years. Their support and care helped me overcome setbacks and stay focused on my graduate study. I greatly value their friendship and I deeply appreciate their belief in me. I am also grateful to the Indian families that helped me adjust to a new country.
Most importantly, none of this would have been possible without the love and patience of my family. My immediate family to whom this dissertation is dedicated to, has been a constant source of love, concern, support and strength all these years. I would like to express my heart-felt gratitude to my family. My extended family has aided and encouraged me throughout this endeavor. I have to give a special mention for the support given by Dr. Gireesh Bhaskaran, J. C. Jagannadham and T. Subbalakshmi. I warmly appreciate the generosity and understanding of my extended family.
Finally, I appreciate the financial support from AFOSR and ONR that funded parts of the research discussed in this dissertation.