The ancient game of checkers (or draughts) has been pronounced dead. The game was killed by the publication of a mathematical proof showing that draughts always results in a draw when neither player makes a mistake. For computer-game aficionados, the game is now "solved".
The computer proof took Jonathan Schaeffer, a computer-games expert at the University of Alberta in Canada, 18 years to complete and is one of the longest running computations in history...
At its peak, Schaeffer had 200 desktop computers working on the problem full time, although in later years he reduced this to 50 or so. "The problem is such that if I made a mistake 10 years ago, all the work from then on would be wrong," says Schaeffer. "So I've been fanatical about checking for errors."
--Justin Mullins, New Scientist, on the end of checkers