39
votes
Accepted
Is there a balanced chess system where players of unknown skill can have an equal chance of winning?
Yes.
The way I've done this in the past is to play a series of games with clocks starting with 10 minutes each on the clocks and then the rule for subsequent games that the winner of the previous ...
- 94.5k
39
votes
Why can't I move my knight from d5 to c7?
Indeed, if this is a normal game of chess, then here White can play Nd5-c7. In fact that looks like the best available move. The red move Rxa5 actually looks like the worst available move. One issue ...
- 1,415
28
votes
Is there any position where not promoting (illegally) would be the best move?
Here is an example:
[fen "8/4P3/8/4p1p1/2p3Pp/p4p1K/k1p2P1P/8 w - - 0 1"]
1. e8 leads to stalemate next move, while all legal promotions lose to 1... c1=Q followed by 2... Qf1#.
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26
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On an infinite board, which pieces are needed to checkmate?
In fact K+R+R can force checkmate against K on an open board.
First move both Rooks away from the King and to different rows and columns.
Then check the King with one Rook, say on a row.
Whichever ...
- 6,524
25
votes
What are the rules of Quantum Chess?
The board and pieces
Quantum chess is played on a regular 8x8 chess board with standard pieces.
Pieces have rings around them, filled in with colour. These rings show the probability that the piece ...
- 2,081
25
votes
Accepted
Moving into check for a draw as black, why is it illegal? Comparison to Racing Kings
Imagine a variation of chess without the rules about check and checkmate, where a player wins simply when he captures his opponent's king. In this variation, Kxd5 loses the game to exd5.
Turns out, ...
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24
votes
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Is there any position where not promoting (illegally) would be the best move?
The Matt Bengtson problem Prof. Elkies mentions is:
[Title "Matt Bengtson, Chess Braintwisters (Burt Hochberg), no. 103. White to move & draw."]
[FEN "4kn2/3p1pPp/4pPpK/6P1/8/2p5/1b6/8 w - - 0 1"]...
- 6,265
24
votes
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Can you solve this chess problem of a lone knight against numerous opposing pieces?
OK
The check must come from the knight (D'uh!)
The black king must be on c5 for the mate
The white king must be used to cover any empty squares to the right of the black king - thus the white king ...
- 4,357
23
votes
Accepted
Chess960 or Chess959?
There is no mention of excluding the regular starting position in Appendix F. of the FIDE Laws of Chess, so it's really Chess960 and not Chess959. I can imagine that there are chess programs or ...
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23
votes
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Is there a name for a chess variant where you are allowed to capture your own pieces?
In German, we would call this "Schlagschach". The German Wikipedia translates this to "Capturechess".
However, I could not find an English resource that describes this variant.
But there is a thread ...
- 473
20
votes
Accepted
Could two kings force checkmate against a lone king?
If these are two real kings, it is not possible. This is because one requirement of checkmate is that the black king is in check which cannot be achieved with any of the white kings, since it would ...
- 20.7k
19
votes
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What are the best openings in Antichess?
It was discovered that e3 is a win for White:
http://magma.maths.usyd.edu.au/~watkins/LOSING_CHESS/ICGA2016.pdf
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19
votes
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Can you castle twice in Chess960?
Excellent question. The rules state that this is not possible. Castling can only be done once.
This is explicitly mentioned under Guidelines II. Chess960 Rules:
II.3.1 Chess960 allows each player to ...
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18
votes
Could two kings force checkmate against a lone king?
A King and a Man (or commoner; i.e., a non-royal King) can mate a lone King. The longest distance to mate on a standard 8x8 board is 18 moves.
The result quoted above was obtained by H.G. Muller in ...
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18
votes
Moving into check for a draw as black, why is it illegal? Comparison to Racing Kings
Those are just the rules of the game. You could absolutely try to make the case that moving into check in such a situation should be legal, but playing by those rules wouldn't be chess anymore (it ...
- 19.8k
18
votes
Accepted
Checkmate in ω² moves with finitely many pieces
Introducing a position of game value ω² with finitely many pieces
In the following position with finitely many pieces, White has mate-in-ω² (Black to move): (For convenience, I put the position into a ...
- 473
17
votes
Moving into check for a draw as black, why is it illegal? Comparison to Racing Kings
I will answer from a different perspective: why Racing Kings (RK) has a rule to allow black a chance to draw, and why the same logic doesn't apply to chess.
What is Racing Kings (RK)?
Background for ...
- 4,980
16
votes
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Would bishops be stronger or weaker on the same coloured squares?
And the correct answer, as always, is: "it depends on the position" :-)
OK, assume that you start with Bb1/Nc1. Lichess says +0.1. But this is the sum of...
the N generally standing a bit ...
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15
votes
Accepted
On an infinite board, which pieces are needed to checkmate?
Here are some mates I found:
Queen and rook (limit the black king until the white arrives to help)
[Title "KQR vs k mate"]
[FEN "1R6/5k2/8/8/8/8/6Q1/K7 w - - 0 1"]
1. Qg8+ Ke7 2. ...
- 4,285
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 ...
- 2,779
14
votes
How do computers play three-check chess?
I have been working on the aforementioned code of Stockfish for three-check chess, so I will try to summarize the most important evaluation changes (in terms of Elo gain) we made compared to standard ...
- 2,346
14
votes
Can one side force a loss in regular chess?
There is likely not a way to force a loss. Selfmates are relatively rare, and one can probably not be forced from the opening position.
The best plan, paradoxically, is likely to try to capture as ...
- 18.4k
13
votes
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How do computers play three-check chess?
https://github.com/ddugovic/Stockfish
Very active development, this is the Stockfish version used by lichess.
What you need to do is search this macro:
#ifdef THREECHECK
Evaluation function:
...
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13
votes
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Official rules for castling in Chess960? (Is there a loophole?)
Hi thanks for your questions Remellion. I have a better answer for Q2 than Q1, but bottom line there is no loophole in the FIDE Laws.
(1) I don't know of and can't locate any other official source of ...
- 11k
13
votes
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How many moves of head start does white need for a guaranteed win?
There is a similar ancient question, but this isn't a duplicate since White may move anywhere.
For an upper bound, I can prove a guaranteed win for White in 5 moves. Indeed, it is reminiscent of ...
- 17.1k
13
votes
On an infinite board, which pieces are needed to checkmate?
An infinite number of knights would be insufficient to force checkmate, assuming the enemy king starts some distance away and not surrounded. The knights are too slow and not enough of them can chase ...
- 18.4k
13
votes
Would bishops be stronger or weaker on the same coloured squares?
Are you familiar with the variant known as Crazyhouse? Basically, if you capture an opponent's piece, you can spend a later turn to place it anywhere you like on the board, as your own piece. This ...
- 862
12
votes
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Checkless Chess
Your "checkless" chess AI would run into problems with the stalemate rule. It would consider the poaition with white king on a6, white pawn a7, black king a8, a win for White because wherever Black ...
- 3,762
12
votes
Is there a balanced chess system where players of unknown skill can have an equal chance of winning?
A common way to have a large number of weak players have a chance at beating a single strong player is simultaneous chess:
image taken from http://www.chesshistory.com/winter/winter89.html
The ...
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12
votes
Accepted
In Hand and Brain chess, is the stronger player generally preferred to be the hand or the brain?
Not a definitive answer, but I'm posting my comment based on the upvotes it received.
It depends. GMs have different opinions.
GM Hikaru Nakamura has said it really depends on the situation. ...
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