  Major advances in Question Answering technology were needed for IBM Watson to
play Jeopardy! at championship level -- the show requires rapid-fire answers to
challenging natural language questions, broad general knowledge, high
precision, and accurate confidence estimates. In addition, Jeopardy! features
four types of decision making carrying great strategic importance: (1) Daily
Double wagering; (2) Final Jeopardy wagering; (3) selecting the next square
when in control of the board; (4) deciding whether to attempt to answer, i.e.,
"buzz in." Using sophisticated strategies for these decisions, that properly
account for the game state and future event probabilities, can significantly
boost a players overall chances to win, when compared with simple "rule of
thumb" strategies. This article presents our approach to developing Watsons
game-playing strategies, comprising development of a faithful simulation model,
and then using learning and Monte-Carlo methods within the simulator to
optimize Watsons strategic decision-making. After giving a detailed description
of each of our game-strategy algorithms, we then focus in particular on
validating the accuracy of the simulators predictions, and documenting
performance improvements using our methods. Quantitative performance benefits
are shown with respect to both simple heuristic strategies, and actual human
contestant performance in historical episodes. We further extend our analysis
of human play to derive a number of valuable and counterintuitive examples
illustrating how human contestants may improve their performance on the show.
