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Old 12-11-2017, 03:50 AM   #26
ChrisV
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

That probably sounds like I'm splitting hairs but engines evaluate win probability based on best responses. So if move A is +0.5 against best response and +0.6 against second best response, and move B is +0.5 against best response and +3 against second best response, the engine will evaluate both of them as +0.5. But I assume (just speculating) that the second best response evaluation would be a tiebreaker and it would play move B.
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Old 12-11-2017, 11:08 AM   #27
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

would missing the openingbook really make that much difference? the general gist I got from watching youtube channels dissect the games is that both play theoretical lines until A0 does something different (I just take their word for it) I assume stockfish is 'out of the book' when that happens anyway
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Old 12-11-2017, 11:57 AM   #28
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

Computer opening books are very thorough, and actually getting the program out of book in a way that is favorable is difficult. That said, I did see some chess programmers criticizing the Stockfish book (maybe because it doesn't force Stockfish to only go down lines that lead to positions that favor computers).
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Old 12-11-2017, 07:21 PM   #29
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

I mean, people have done analysis of the games with a properly running Stockfish. There are some games (eg game 4) where Stockfish makes some dubious moves, but there's also a lot A0 does which is not seen by top engines.
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Old Today, 03:03 AM   #30
David Sklansky
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

How high does your rating have to be such that you fully appreciate these super duper unexpected moves that Alpha made even after being told what they were and seeing how they turned out (but not reading a detailed explanation).
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Old Today, 03:22 AM   #31
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

As high as AlphaZero's, I guess. There's no critical point at which you suddenly move from understanding to non understanding. I am not particularly good at chess (rated around 1800) but I'm able to notice obvious differences in the way A0 plays compared to other engines. It's more aggressive and has better positional understanding. Engine v engine games can often look a bit directionless, with each side just playing moves that don't lose and lacking any real long term plan or understanding. When A0 drops one of its positional binds, you can look back and see that it was working towards that for some time.
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Old Today, 04:37 PM   #32
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

I don't think understanding the individual moves is that hard, especially if you watch some of the videos out there that explain them well, e.g. Jerry from ChessNetwork is doing a good series on it. If there's an overarching theme to AlphaZero's play it appears to include grabbing space and not being afraid to sacrifice material.

Needless to say, understanding the moves after they're made is one thing, and finding them during a game is another.
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Old Today, 05:35 PM   #33
David Sklansky
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

I was talking specifically about those few moves that had two exclamation marks and articles made a big deal of. How good do you need to be to appreciate that specific move if you had been following the game to that point, see that move (which presumably might look strange) are told it is brilliant, but are not told why?
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Old Today, 07:40 PM   #34
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

The moves that are getting publicity aren't really the point.



Here AlphaZero played Bg5!! Now, this move is not hard to understand conceptually. Black's minor pieces are a disaster, huddled on the queen's side doing nothing. The knight on b8 is hemming in the rook and has literally no moves. Black's king theoretically should be weak, and Bg5 is trying to get more pieces around it. The threat if Black does nothing is Nf6, where gxf6 Bxf6+ is mating and if the queen moves say to d3, there's Be4 and it's slaughter time. But Black has various replies to consider to Bg5 (f5, hxg6, Bd3).

So, Black's pieces are not helping the defence of his king and Bg5 is putting more pieces around the king and issuing a direct threat. That's all easy. But understanding that the move actually works - working through all the tactics and figuring out that they work for White - well, other engines take a very long time to find Bg5. Which means that the tactics will be beyond human ability to calculate. So Bg5 can be understood conceptually, but not verified (without the assistance of an engine). But that's true of tactical moves Stockfish makes as well. The tactical capabilities of engines have outstripped humans for ages. The reason people are making a big deal out of it is that one might expect that a pattern-recognition approach might have tactical capabilities inferior to that of a brute-force engine, but in fact here it is finding a tactical move which brute-force engines struggle to find.

The impressive thing for me about AlphaZero is its positional understanding, though. And there, you can't pull out single moves. You have to look at a game holistically. When AlphaZero drops one of its positional binds, you can look back through the game and note moves which contributed to A0 getting exactly the pawn structure it wanted, say. And again, while it's easy to pull out features of a move and say "oh yes, see, moving this pawn here establishes control of these squares" - that doesn't mean the moves are really understood. There might be second, third, and fourth more subtle aspects to the move that didn't become apparent in the game.

Last edited by ChrisV; Today at 07:45 PM.
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Old Today, 07:56 PM   #35
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Re: Google's AlphaZero AI Learns Chess in Four Hours; Then Beats Stockfish 28-0-72

That position above is actually a good illustration of the way the games went. AlphaZero disdains material and goes for positional advantage instead. White is a pawn down but has huge positional compensation - Stockfish (not seeing Bg5) thinks the position is about equal, and in the released 10 games, AlphaZero is always choosing to take the positional advantage side of these imbalances. It's exciting to see because the message from engines so far has been "Human abstract positional ideas are subordinate to the concrete moves of a position; lol 'positional advantage', I have an extra pawn and can see 20 moves into the future". Engines grab material in positions where it looks too dangerous to human and then defend tenaciously, repeatedly finding the only defensive move available. But A0's play is demonstrating that maybe engines are wrong about that and that positional ideas do trump concrete material a lot of the time. And here, the punishment for Stockfish's greediness comes in the form of a tactical shot, but in other games, AlphaZero simply continues to improve its positional advantage until it becomes overwhelming and something breaks in Stockfish's position.

Last edited by ChrisV; Today at 08:03 PM.
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