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48 votes
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Why does Stockfish undervalue pawns when compared to the classical "a piece is worth three pawns" approach?

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 ...
user1583209's user avatar
  • 20.8k
38 votes
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Should a chess engine be aware of opposite-side castling?

I'm pretty sure Stockfish doesn't have explicit code that handles opposite-side castling. What it does have is: Some kind of "menace" score for enemy pawns advancing against our king. The ...
Allure's user avatar
  • 27.7k
29 votes

Is chess a zero sum game?

When I said chess is a zero sum game in that answer, I wasn't referring to anything involving ratings. Obviously if we include ratings then chess isn't strictly a zero sum game, since the gains and ...
Inertial Ignorance's user avatar
28 votes

Is this a draw despite the Stockfish evaluation of −5?

This is a fortress and a draw. The black king can't advance as the rook, shuffling between h3 and f3, prevents it. The only way to break the fortress is to trade the queen for the rook and pawn, but ...
Mike Jones's user avatar
  • 5,169
27 votes

Why don't chess engines take into account the time left by each player?

Why don't chess engines take into account the time left by each player? For the simple reason that there is no way of knowing how to do that. A few years ago a clubmate rated about 1800 playing in ...
Brian Towers's user avatar
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22 votes

Is chess a zero sum game?

Chess is a zero sum game. There is 1 point available and it is divided over the players, what one gains the other loses. It is a simple concept with a simple answer. Tournament rules mention some very ...
RemcoGerlich's user avatar
22 votes
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Is this a draw despite the Stockfish evaluation of −5?

This position is a standard classical fortress. There is no way the Black color can go through as long as White just shuffle pieces, wait and do nothing silly. Stockfish is a computer algorithm, it ...
SmallChess's user avatar
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20 votes
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How do chess engines decide which best line to play when the game outcome is within their horizon?

If the engine can choose between getting mated in 2 or mated in 3, it'll choose the line where it is mated in 3 (even though the mate in 2 might be 'more difficult' to spot for humans). It can't ...
Glorfindel's user avatar
  • 24.9k
20 votes

Is there an engine evaluation technique that factors in 'time'?

Is there any established system for evaluating positions taking into account time for both players? No, there isn't. This is for two main reasons: There is no objective measure for how time affects ...
Brian Towers's user avatar
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20 votes
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Does blitz change the relative value of position vs material?

It just seemed obvious to me that gambits would work better with faster games, for the same reasons as given in the comments - it's harder to defend than attack, etc. I tried looking at several ...
D M's user avatar
  • 19.6k
20 votes

Why don't chess engines take into account the time left by each player?

Because engines find the best move by assuming best play, not by hoping their opponent makes an inferior move. If you constructed an engine whose sole purpose was to beat a specific person/engine, ...
BlueRaja - Danny Pflughoeft's user avatar
19 votes
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Why is this position in the 3.d4 d5 Petroff equal?

What I can't wrap my head around is that Stockfish says that this position is completely equal. Why is that? Black has the bishop pair in a completely open position (no center pawns). This advantage ...
Brian Towers's user avatar
  • 97.9k
18 votes
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How are the scores decided in Chess?

Those aren't scores; there are just three possible scores in chess: White wins, Black wins, and draw. Those are evaluations of the chess engine; a score of +0.62 means the engine thinks White's ...
Glorfindel's user avatar
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18 votes
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Why is 11. .. h6 such a bad move?

By playing 11...h6, you created a weakness on g6, and you created a target on h6, now it is easier for white to open up a position around your king by pushing their g-pawn. White also has a potential ...
Akavall's user avatar
  • 6,486
16 votes
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Stockfish: What is the maximum (minimum) centipawn score that a position might be evaluated at?

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 ...
Chromatix's user avatar
  • 1,679
16 votes

Should a chess engine be aware of opposite-side castling?

Interesting question. I think it depends on how much bottom-up intelligence the engine has. For example, AlphaZero was given no explicit heuristics, but was able to infer plenty of strategy by playing ...
Inertial Ignorance's user avatar
15 votes

How would the min max algorithm of a chess engine work in the case of 3 player chess?

The problem is really not in chess, but in any naive 3-player version of any 2-player strategy game. In general, it is hard to make an interesting 3-player game where each player's performance is ...
user21820's user avatar
  • 2,816
14 votes
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How do chess engines evaluate a position if the position is in the middle of an exchange?

A good chess engine won't stop after a predetermined number of moves, but will keep looking until the position is "quiescent", which roughly speaking means that there are no pending captures or checks....
itub's user avatar
  • 10.6k
14 votes
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How to analyse positions more accurately as a total beginner?

The bishop is beautifully placed. No, it isn't! It is semi-bad. There is a chess expression - "Biting on granite". If Black had pawns on f7, e6 and d5 your bishop would be "biting on ...
Brian Towers's user avatar
  • 97.9k
13 votes
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Why is this position considered to give white a significant advantage?

[FEN "r4rk1/2p1qppp/1p3n2/p7/2B4B/4P3/PPQN1Pbb/2KRR3 w - - 0 1"] 1. f3 {traps the bishop} Rad8 2. Re2 Bxf3 (2...Bd6 Rxg2 Kh8 Rh1 {the Black king is not safe at all}) 3. Bxf6 Qxf6 (3...gxf6 ...
B.Swan's user avatar
  • 3,488
12 votes

Why is 11. .. h6 such a bad move?

To add to the existing answers, you just gave up your light squared bishop for no apparent reason, while creating many light square weaknesses around your king with the same move! Now white is the ...
YiFan's user avatar
  • 614
11 votes
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Oscillating Stockfish Evaluation on Laptop

If I understand correctly your x axis is the moves. Your script implied Anand and Prag were blundering every time they make a move, Clearly you have a bug in your script. Stockfish engine always give ...
SmallChess's user avatar
  • 22.5k
11 votes

Why does Stockfish suggest capturing a bishop in this position when my opponent can fork my king and rook?

I agree with the other two answers, but I feel like I also need to comment on the beginning of the game since there was A LOT more important stuff there than just the answer to why Qxg5. This is very ...
PhishMaster's user avatar
  • 32.6k
11 votes
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Why is this "slow move" with the king a good move?

Just because Stockfish thinks a move is best doesn't mean it is best. But let's see why Stockfish might like it. When I look at Stockfish's static evaluation of that position, and move the king from ...
D M's user avatar
  • 19.6k
10 votes
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Queenless Imbalanced Middlegame

First, I don't think that there is any doubt that black has significant compensation, but clearly, black is still trying to hold this, not win it when talking two computers playing each other. I ...
PhishMaster's user avatar
  • 32.6k
10 votes
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Why does Stockfish suggest capturing a bishop in this position when my opponent can fork my king and rook?

White does indeed fork the king & rook after Nc7+ - but after Nxa8, the knight is not escaping, so Black is at worst even on material. [FEN ""] 1. d4 c5 2. Nf3 cxd4 3. Nxd4 Nc6 4. Nc3 e5 5. ...
Allure's user avatar
  • 27.7k
10 votes

Why does Stockfish undervalue pawns when compared to the classical "a piece is worth three pawns" approach?

Please note that those values are "abstract", later to be modified by the specifics of the position. For example, even though a knight appears 0.8 pawns less valuable than a bishop, it could be that ...
David's user avatar
  • 16.3k
10 votes
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Lichess endgame evaluation

Unless you explicitly hard-code these endgames, or provide the computer with endgame tablebases, they will apply what they've always done throughout the game: search lines and return the static eval (...
Allure's user avatar
  • 27.7k
10 votes
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How come it's actually Black with the advantage here?

White's actually quite close to busted in that position after 16...Qd5. Of the two points you bring up, note that White doesn't actually control the e-file because Black is ready to play a rook to e8 ...
Allure's user avatar
  • 27.7k

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