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Comment by umutisik | Hacker News Reader

If “accuracy” measures how well a player matches computer chess, then as players continue to study more and more with chess programs, you would expect their play to match the programs more and more.

Personally I find it odd to measure how well the players match the computer program and call it accuracy. The computers do not open the game tree exhaustively so they give only one prediction of true min-max accuracy.

When Lee Sedol made move 78 in game 4 against AlphaGo, it reduced his accuracy but won him the game.

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Move 78 was humanity's last great stand against AI in a board game. Lee Sedol, tired and inspired, reddens AlphaGo's ears with a move plucked from a higher dimension.

It now seems humorous that Kasparov once accused people of helping computers behind the scenes. Now chess masters have been caught huddled in bathroom stalls with their smart phones. Chess commentators choose to willfully ignore chess engines in their presentations, in order to enable our understanding of the analysis. The torch has been passed.

We should be clear: move 78 didn’t really work, except that the engine got confused. Other humans and later versions of Go engines can refute it.

It was a divine move in the sense that he created a surprise tsumego that crashed AG. Lee Sedol called it his 'trick move' in the post game interview I believe. Move 78 shouldn't have damaged AlphaGo's moyo if it had responded correctly. See diagram 9 here for an explanation: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/viewer.html?pdfurl=https%3A%2F%2Fdeepmind-media.storage.googleapis.com%2Falphago%2Fpdf-files%2Fenglish%2Fls-vs-ag4%2FLS%2520vs%2520AG%2520-%2520G4%2520-%2520English.pdf&clen=4258493&chunk=true

I don't know if this is a thing, but chess players might also steer the game in a direction/position which their opponent hasn't studied much, but they have. There's a "social" side to this seemingly "mathematical" game, no?

This is more so in the opening (the beginning of the game, and separately where engines tend to be a bit less informative) but yes it is definitely part of the chess metagame, and you'll often see commentators talk about whether someone is "still in prep" or has gotten out of it. It often can lead to time advantages if one gets an opponent out of prep.

Fabiano Caruana (previous World Championship challenger) has said that he’s happy to find lines where the machines have you slightly behind, purely because they’re less like to have been studied in detail by your opponent. Even with perfect recall of the first 20/30 moves in various lines, players are still going to steer away from some lines based on their and their opponent’s strengths (tough against super GMs with few weaknesses though). So you’re definitely right, I think there’s a lot of game theory here, albeit much of it settled by your team ahead of the actual match.

This is addressed in the article by the way.

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