knoW LE D GEM TS This re search was con ducted under the supervision of Yoav Shoham, whose intellec- tual rigor and insight have been a con st ant source of en couragement and inspiration Valuable perspectives and gui dance h ave al so been provided by Terry Winograd and Rob Barrett, who both induced greater clarity of thinking and present ation Daphne Koller and Cliff Nass supplied helpful pointers to related areas of re search as members of my orals committee. A thorough groun ding in AI systems and archi lectures was provided by earlier advisors Carole Klein at Cambridge University and both barbara haves-Roth and Nils Nilsson at St an ford Universit ddition, Andy Hopper at Cambridge University provided the initial en couragement to un dertake doctoral rese arch Over the ne arly six years I have been at the Depart ment of Computer Scien ce at St anford University. t here have been const ant valuable interactions with members of the various research groups focussed on creating AI agents(or 'bots) which reason or learn(Alot s, Bots, Nobotics and Nobot s), as well as the People, Computers and Design group focus sed on interaction design, and, most recently, the Digit al Libraries Project, working on many different technologies in support of information seeking tasks. Outside of St anford, I have gained a wider perspective on interaction de sign and prototyping from Mik Lamming and Mike Flynn at the Xerox Research Center in Cambridge, and a better underst anding of real-world technology design and development from James Rucker and Marcos Polan co at Imana in San franciscoAcknowledgements This research was conducted under the supervision of Yoav Shoham, whose intellec￾tual rigor and insight have been a constant source of encouragement and inspiration. Valuable perspectives and guidance have also been provided by Terry Winograd and Rob Barrett, who both induced greater clarity of thinking and presentation. Daphne Koller and Cli Nass supplied helpful pointers to related areas of research as members of my orals committee. A thorough grounding in AI systems and archi￾tectures was provided by earlier advisors Carole Klein at Cambridge University and both Barbara Hayes-Roth and Nils Nilsson at Stanford University; in addition, Andy Hopper at Cambridge University provided the initial encouragement to undertake doctoral research. Over the nearly six years I have been at the Department of Computer Science at Stanford University, there have been constant valuable interactions with members of the various research groups focussed on creating AI agents (or `bots) which reason or learn (AIbots, Bots, Nobotics and Nobots), as well as the People, Computers and Design group focussed on interaction design, and, most recently, the Digital Libraries Pro ject, working on many dierent technologies in support of information seeking tasks. Outside of Stanford, I have gained a wider perspective on interaction design and prototyping from Mik Lamming and Mike Flynn at the Xerox Research Center in Cambridge, and a better understanding of real-world technology design and development from James Rucker and Marcos Polanco at Imana in San Francisco. vii