Commentary for black move 14:

AUDIENCE MEMBER: Usually the -- you said the computer looks at every possible move. So if it has at some point, 50 moves or so, analyzed every possible move, or at some point does it prune out some moves? Because if it does analyze any move then I don't think it can go beyond a ply of seven or eight, which goes to a depth --

DB MOVE: 14...Ng6.

MAURICE ASHLEY: A very natural move at this point. And we are expecting the move h3-h4 by Kasparov in order to stop, preempt this possibility of h5-h4. But to repeat the question, Yaz, if the computer is looking at all these moves k it really look that deep?

YASSER SEIRAWAN: Yes, that's the whole point. With this parallel processing technology, the computer essentially has an assembly line, if you will, of microcomputer processors. And the computer sends instructions to each of these processors and says, "Here say problem. Work on it, report back to us." And through this massive parallel processing, you get incredential calculations. 200 million positions per second translates to 12 billion positions per minute. Deep Blue has an internal time control of three minutes a move, which is 36 billion positions. That's a lot of positions. It seeds a -- sees a lot of possibilities, and what's even worse, it gets worse. The worst part is the computer thinks when Kasparov is thinking. So when Garry goes into his 15-minute meditations as he says, "Okay, what am I going to do to set up victory," the computer may look at half a trillion positions --

MAURICE ASHLEY: Easily.

YASSER SEIRAWAN: -- over the course of a half an hour. That's phenomenal.

MAURICE ASHLEY: That number is so astounding, one has to wonder how the heck has Kasparov played a decent game of chess against this thing. But in fact, in point of fact all those moves it's looking at are not great moves.

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