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Comment by atrudeau | Hacker News Reader

For those joining the stream now, can anyone indicate the current state of the match? Is AlphaGo already dominating? I keep waiting for the commentators to give their opinion but they haven't so far.

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Myungwan Kim 9d said white (AlphaGo) is probably a little bit ahead, if I heard correctly. But hopefully someone else has been following the AGA stream (https://www.youtube.com/watch?v=rFNgHXjIJo4) more closely and can confirm/deny–I've been switching between the AGA and main streams, so I've only caught snippets.

EDIT: probably around 10+ point lead for AlphaGo at this point according to Myungwan's stream.

It's hard to say since Alpha Go's style is not about maximizing a score difference but about maximizing a probability of winning.

This is a really, really important point to consider. AlphaGo does not care if it wins by a half point or twenty points. Increasing your margin of victory past your margin of error is one way of achieving victory, but simply reducing your margin of error below your current margin of victory can be just as effective an approach in many situations.

If AlphaGo is highly confident in its ability to reach an effective draw in other areas of the board, it will happily enter a line in the current area of play that only nets it a stone or two, rather than going for more material at the cost of uncertainty in the remaining areas in play.

How do you know that? A NN often maximizes its performance against a goal

During the first game against Lee Sedol commenters labeled many Alpha Go moves as "mistakes", as well as "slow". It wasn't until the end when they started seeing the results of those moves.

It's been mentioned. Also when building the best Go bot would they try to maximise it's win rate instead of getting larger winning margins but winning less often?

From the explanations of how AlphaGo was architectured and trained: The goal being maximized isn't stone difference, rather probability of winning.

> it will happily enter a line in the current area of play that only nets it a stone or two

heck, it will enter a line of play that loses it a stone or two, as long as it considers that line of play to provide the highest board state values, and eventually a win.

Neither do the players. As a player you maximize your chances of winning as well.

As an ex-go player (I pretty much stopped completely) I don't agree with your statement. You of course want to maximize your chances of winning but that means getting the most out of the current situation. If there's a play that you believe is a 10 point move and there's an 8 point move you're going to make the 10 point move 99% (probably 100% actually) of the time if they both keep initiative.

I'd play the 8 point move if I was ahead and it was more solid.

The problem is you don't know if it's more solid. That's why people go for bigger wins with smaller probabilities, like lottery, or any gambling. Humans are not that good with probabilities.

Only if you assess the chance of winning is the same for both. A rich man doesnt pick a fight, says the proverb.

The problem is, AlphaGo can read the "chances for winning" vastly better than any human being. AlphaGo may calculate a "chance to win" of 99.6% to 99.5%, and it will then select the 99.6%, even if that's taking 8 over 10. A human simply can't do that. That "close" of a winning probability looks the same, even to a master at whatever game they are playing.

This is literally why chess computers have gotten to the point that no one can beat them.

Thats not the problem, thats alphago simply playing better than human beings. Its not related to the strategy of highest probability of winning, human players also maximize that, its just that alphago is doing it better by now.

Arguing that they are the same is incredibly naive. There's no human being playing this game by calculating the odds of a given move resulting in a win then choosing the move that results in the highest possibility. Human players can't maximize that, because we aren't capable of those types of calculations. Instead, we use a variety of other techniques (instinct, skill, etc) to determine the next best move.

Go players, even bad ones, often play moves that simplify a position -- capture "dead" stones, remove aji -- even though they aren't the largest points value available on the board. We do what we can to reduce uncertainty in the service of maximizing win probability even in the face of being bad calculators.

Yes, but they're essentially just scraping the surface of those types of moves. In chess it's similar — I'll happily trade down "losing" material to a won endgame. But humans do these things typically only when they can get to an ending where they're 95%+ sure they will win.

AlphaGo will do this in any situation, from the beginning of the game all the way to the end.

Ok, so Michael Redmond just came on along with this other girl. He said AlphaGo made a few weird moves, but didn't give an opinion of which way the game is tending (though I felt from his tone that he thought Ke Jie might have a chance). The girl said she was following some Chinese players' group and the talk there was that the game was even.

UPDATE: Redmond just did an early count and AlphaGo is slightly ahead.

UPDATE: Commentator thinks the Ke Jie has basically no chance at this point.

Personally I like ke jie's position so far, but it looks even. The die has not been cast.

Was there a "move 37" type moment in this match for you? Or are all of AlphaGo's best tricks already "old hat" after the Master series?

The only surprising moves by AlphaGo were the slow-looking moves on the left, playing in Gote with a dead group.

Other than that, there were no bot surprises.

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