@JLV
They knew how to beat chess grandmasters from the very first chess program that did a tree search to rate different moves, they just lacked computing power at that point. The first computer to beat a human in a tournament (not grandmaster level I'm sure, but still if a person is going to enter a tournament you figure they are halfway decent) was in the late 60s.
If they had the computing power Google is throwing at Go available to them in the late 60s, that chess playing computer probably could have beat grandmasters. The improvements they made to chess programs since then - aside from the massive increase in computing power available to them - consisted of various improvements to the tree search to prune unproductive paths and do better position evaluation in the endgame. If we had to run it on a 1960s era computer, even with modern techniques a chess program wouldn't be all that much better, and Go would still look impossible.
We haven't got any closer to real AI during all that time, AI researchers have just got better at marketing their work to a credulous public who thinks beating humans in chess or Go gets us closer to that goal. It doesn't, because expert human players don't play those games by evaluating trillions of moves and choosing the best one. We still don't have a clue HOW they do it, in fact.
Biting the hand that feeds IT
