I would avoid thinking of this like a traditional computer program that just "bugged out" due to a glitch or a problem in the software. More accurately, it failed to account for the implications of a move on the board and therefore focused its attention in the wrong place. This happens often in games, I can imagine that a chess master playing an amateur might move his knight or bishop into a position that does immediately seem threatening to an amateur, so the amateur responds by moving a pawn somewhere else on the board, while the correct move would have been to attempt to counter the threat. As should be well known by now, in Go you cannot examine the implications of all possible moves, so some things will be missed. In this case, it seems something important was missed at the time, and the implications were not realized by the program until 10 or 15 turns later.
I mean that it bugged out because the moves it made after missing the exchange in the middle were moves that were obviously wrong, not in a "maybe it's up to something" kind of way, but in an objectively 100% bad kind of way. Even if you can't analyze all possibilities AlphaGo made a number of moves that made absolutely no sense at all even to way lower level players.
> a number of moves that made absolutely no sense at all even to way lower level players.
Another possibility is that it was looking way deeper than anybody, and there was a 1% chance or turning the whole game around with those seemingly bad moves. But Lee Sedol blocked that deep move in a way nobody was able to see.
He's right. The 9d commentators just laughed them off. They were the kinds of moves a 25k might play hoping that his opponent would make a silly mistake. That's exactly what AlphaGo was trying to do. The moves it played did have a "slight" chance of working, if Lee Sedol had responded incorrectly, but that would have never happened. They were the kinds of moves that are insulting when an opponent plays them against me and I'm just a weak amateur player. The moves clearly had no depth to them, and everyone that understands the game agrees on that.
