Create an Ajax mindreader application with E4X and Prototype, Part 2: Make the mindreader smarter

In this two-part article series, you learn to use both ECMAScript for XML
(E4X) and the Prototype JavaScript library to create a simple Ajax mindreader
application that plays Twenty Questions and learns about new objects as it goes
along. In Part 1, you learned to create a system that takes an existing
knowledge base and analyzes it to determine what the user might be thinking. Now in
Part 2, you'll learn to add new information to the knowledge base, and to use the
Prototype JavaScript library to integrate the Twenty Questions application with an
external database so training by one user is usable by others who play the game.