"The Next Move"
featuring Dr. Altha Rodin

Video

Handout

Since the late 1980s, a computer program called Chinook has been quietly rising through the ranks of checkers players, both mechanical and human. Nobody took much notice until 2007, when the program's creators made a startling announcement: Chinook had become so strong that it was now incapable of losing a game.

How did the Chinook team know that they had created an invincible checkers machine? On March 1, 2014, Dr. Altha Rodin introduced us to the most basic versions of some of the techniques involved. Instead of complicated games like checkers, we focused on deceptively simple-looking (and relatively unheard-of) games like Subtraction, The White Knight, Nim, and Japheth's Nim.

Playing and thinking about Subtraction led us not only to a winning strategy, but also to the idea of a position graph: a map of all the possible positions and moves in a game. We were able to use a position graph to find a winning strategy for The White Knight, but we tackled the much more complex game of Nim, we couldn't get very far. We were stuck until we learned that Nim is mathematically identical to a very different-looking game, called Japheth's Nim, which was much easier to think about.

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