60

The answer is that they either played it on some very handicapped mode, they took back A LOT of moves, or they are probably lying. Stockfish 11 is currently rated about 3607, and that is in standard chess. Computer programs are typically even HARDER to beat for humans at even faster controls. There is a reason elite humans have not played matches against ...


48

I am not an expert on stockfish source code, but my understanding is the following. Humans: It is true, that the 1 piece equals 3 pawns approach is pretty accurate, surprisingly so. However as you are probably aware, when evaluating a position, we consider many other aspects as well, such as piece activity, space, king safety, etc. The difference however ...


41

It's absolutely beatable, but not by an unassisted human. Anyone who claims to have done so is either lying or stacked the deck super heavily in their favor (e.g., by having Stockfish search only to depth 2). "Slow computer" isn't good enough - Stockfish 11 running on 1999 hardware would still have handily beaten Kasparov. You will need help from another ...


36

Page 5 in the paper has your answer: ... AlphaZero compensates for the lower number of evaluations by using its deep neural network to costs much more selectively on the most promising variations - arguably a more "human-like" approach to chess ... "selectively" is the key word. What does that mean? Let's use this following position for our example: ...


32

Mihail Marin simply missed that 1.Ng6 is winning, even faster than 1.Qg6. During opening analysis, and even during a game, sometimes when you find a satisfying continuation you forget to follow Lasker's advice and look for an even stronger one. This is a slight mistake in his analysis, but his evaluation of the variation remains correct (White is winning, ...


28

I think it is because 21.Rfc1 wins the c7 pawn. If black responds with a queen trade, she can't defend the pawn on c7 because white's bishop can attack a defending rook on c8 or d7. [White "NN"] [Black "NN"] [FEN "3r3r/2p1kppp/B2qp3/2Qp4/6b1/PP2P3/3N1PPP/R4RK1 w - - 0 1"] 1. Rfc1 Qxc5 2. Rxc5 Kd7 3. Rac1 {and the pawn falls} That said, the position is ...


27

This is not a blunder, expected behaviour from the engine. Everything worked as intended. Try to copy the FEN string out, and you'll know. Although the position looked winning, White didn't have enough moves to force checkmate before the 50 moves rule. Stockfish, knowing the position was a dead draw immediately asked for simplification. The position you ...


26

Good question. I let Stockfish 11 think on the position, and even by around depth 25-26 it didn't suggest Bf6. But like in your case, after making the move on the board, Stockfish suddenly realizes it is the best move. Although what's also odd is that after Bf6 gxf6 Qxf6, it takes Stockfish longer than at least depth 27 to realize it's a mate in 9 moves/18 ...


24

Just for completeness, I would like to add more explicit instructions for using stockfish in Scid, because sometimes it is a little confusing how to get stockfish to function in an actual chess program. sudo apt-get install scid sudo apt-get install stockfish Load Scid In Scid Click: Tools -> Analysis Engine (click twice) -> New Set Name to ‘...


24

It is true that Rfc1 wins the c7 pawn, but even if that where not the case, Rfc1 is significantly better technique than initiating the exchange yourself. The black queen is pinned against the king, so there is no risk of black evading the queen exchange. Stepping out of the pin will just waste a tempo, because then you'll still be able to exchange. If ...


24

Stockfish isn't a perfect chess-playing entity, and you've found a position where it's unable to tell is a draw (at least until the 50 move rule kicks in and helps it prune). These positions are called "fortresses". You can tell this is happening because even if you input the solution, Stockfish still evaluates the final position as -10 or more. These ...


23

The answer is "No". If you have a defined fixed set of resources - CPUs, memory, cache, etc. - and you allow one engine to have full use of them then that engine is going to be able to analyse to a greater depth than if you take the same set of resources and split them in some way between several different engines. Inevitably the single engine ...


22

If you're curious about the Stockfish code, it can be found here: si->checkersBB = attackers_to(square<KING>(sideToMove)) & pieces(~sideToMove); We call the attackers_to method to figure out if any pieces are attacking the king's position, including pieces on the king's side. Bitboard Position::attackers_to(Square s, Bitboard occupied) const ...


20

That's why I wonder whether there have been any attempts made to provide comparable hardware to both. This is Google you're talking about! So the answer is obviously "No". From the original paper hardware used for initialising and training - Training proceeded for 700,000 steps (mini-batches of size 4,096) starting from randomly initialised ...


19

Both moves lead to crushingly won positions for White, so all things considered it doesn't matter which one you choose. For me, Stockfish shows +14 for Nxg8+ and +9 for Nxd7. The difference between +9 and +14 is a lot less significant than the difference between, say, +0.5 and +2.5. About the material calculation you gave: Nxd7 costs two minor pieces for the ...


18

How does AlphaZero select a move in the search? This is very obvious from the paper. Each simulation proceeds by selecting in each state s a move a with low visit count, high move probability and high vale selecting ... What does that mean? AlphaZero has trained probabilities for each move (end of page 2 in the paper) from a deep neural network. During ...


17

Most strong engines emphasize looking very deeply, at the expense of having a superficial evaluation function. In the AlphaZero paper, they say that Stockfish looks at 70 million positions per second. Human grandmasters look at very few positions indeed compared to engines, but they have a better feeling who is better in a given position. AlphaZero looked ...


17

Where and how in Stockfish's code is check detected? This is simple engine programming. You will need to build a bitboard of the attacking squares and two bitboards of your king, one for each color. You will then run AND on the two bitboards. If the result is non-zero, you know the king is in check. I can show you the code in Stockfish, but does my answer ...


16

You can't really objectively answer this question, but I'll share my view. One of the important factors to take into account is that Leela Chess Zero project requires tremendous computational resources to complete. The way project attains those resources is by convincing large number of people to donate part of their machine time to that project. To make ...


15

play the game until six pieces Stockfish doesn't do that, that's not what tablebase is for. Briefly, tablebase boosts engine search well before six-men position reached on the board. Let's do an exercise, add the board 5 pieces. Now you have 10 pieces on the board, and it's not something you can find in any tablebase. However, during the engine search ...


15

No, an ensemble of chess engines won't beat the best one. The reason is simply because of hardware. Let's take the strongest CPU engines right now to keep things simple. These are Stockfish, Komodo, Leela-CPU, Ethereal, Fire, and rofChade. Stockfish is the strongest. You have a four-core computer, running Stockfish. It's expected to beat all the other ...


14

Well, it is a small sample, but assuming that there are a lot more games like these, I think it could be the following things. First, I am not sure when we first humans first decided that space was an advantage, but for as long as I have been playing, it has been a known factor. Both of these openings cede space compared to double-king-pawn openings and ...


14

The best way to normalise a centipawn score to [-1,+1] range is using a sigmoid function, as that closely approximates the likelihood of a given centipawn advantage converting to a win, and avoids the need to identify a strict maximum or minimum. This is discussed here.


14

Your question has nothing to do with Stockfish. Though it may be interesting to check the original source code. This is purely algorithmic. One dumb solution would be implementing a boolean function (is_check) that takes an array as input representing the board. Only white pieces can check the black king, except the white king and vice versa. If one of the ...


13

First download StockFish. You click on the button shown in the below image and choose "Save as". It will be saved as .rar file, which you can open with WinRar, 7Zip or similar utility... Then you unzip it ( put it where you want ). After that run Fritz, and choose Engine -> Create UCI engine like in the picture below: The following dialog box will pop up, ...


13

Of course there's a way: I'm going to show you one way of doing it on your own, using only free software. We'll write a small script in Python (I'm using v2.7) and only use the wonderful python-chess library (licensed under GPL3, note that I'm using the version 0.14.0). In short, the script will first load up the engine, we will stick to free and open ...


13

AlphaZero already seems to play like a regular "centaur" -> correspodence GM with an engine assistance. As an FM I'd get much more enjoyment of playing AlphaZero vs a regular engine. One comparison would be it plays like Karpov would with perfect tactics. (Game 9 AlphaZero plays a piece down for 15moves which is very Tal like). It is not just style, ...


12

Stockfish assumes that all FEN positions you feed it are legal positions. If you feed it an illegal position and ask it to evaluate it, it will likely crash: Stockfish 5 64 by Tord Romstad, Marco Costalba and Joona Kiiski position fen 4k3/4p3/8/8/8/8/8/3KP3 go depth 14 Segmentation fault: 11 But you could use a Python library such as Chessnut to validate ...


12

I think it's best if I elaborate on your second point with an example move in the game 1 between AlphaZero and Stockfish which also served to satisfy my curiosity today. the time limit of 1 min/move (How would this disadvantage Stockfish?) Stockfish's performance is dependent upon both the time limit and the hardware configuration, so just think of when ...


12

The game ended because of the 50-Move-Rule. From Wikipedia: The fifty-move rule in chess states that a player can claim a draw if no capture has been made and no pawn has been moved in the last fifty moves (for this purpose a "move" consists of a player completing their turn followed by the opponent completing their turn). The last capture was made by ...


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