Author Topic: Even Chess  (Read 108 times)

Steve Brown

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Even Chess
« on: April 23, 2018, 06:01:26 pm »
Imagine a duel between Adam and Bart, who stand a hundred feet apart and take turns shooting at each other. Adam wins a coin toss and shoots first. He has the advantage of the first shot because if he kills Bart, he has had one more chance than Bart had to kill his opponent. If Bart could somehow take a shot at Adam after being killed, the duel would be fought on even terms. An analogous situation exists with chess. If white checkmates black, the game is over, and the number of moves white has played exceeds the number of moves black has played by one. If a game ends with "20 Qg7 mate ...", white has moved 20 times and black has moved 19 times. White has the advantage of the first move. This does not mean that chess is inherently unfair, because in a match or tournament, players alternate playing white and black. I devised a variant named Even Chess so that a single game can be played on more even terms, not to make chess more fair but to modify the game in new and interesting ways. Even Chess allows black to develop more aggressively in the opening and to have less reluctance to counter-attack, instead of defend, when under attack by white.

Even Chess is played as orthodox chess but with a few changes to the rules. The first is that the game ends only after both players have made the same number of moves. Instead of checkmate, the object is to capture the opponent's king. The game ends after black's move when one or both kings have been captured. If both kings are captured, the result is a draw. A player is not required to get out of check but may respond to a check on his king by placing the opponent's king in check, or by making some other move. For example, if white places the black king in check, black may respond by placing the white king in check. If white then captures the black king, black may capture the white king, and the game is a draw. White can avoid the draw by getting his king out of check, leaving the black king in check. Then if black does not get out of check, white may capture the black king and wins if black does not then capture the white king. Exposing one's own king to check, or leaving it exposed to check, is a legal move. In the case where white responds to a check on his king by checking the black king or making some other move, he loses immediately if black then captures the white king. In Even Chess, it is possible to blunder into a loss by overlooking a check on one's own king and making a move that does not parry the check. Announcing "check" is not required but may be done as a courtesy. 

Another rule concerns castling. In orthodox chess, a player may not castle out of check. In the opening, an important consideration is to castle before losing the right to castle because of a check. Losing that right can inflict serious weakness in the player's position. Playing one move behind white, black is more susceptible to losing the right to castle, so has to attend to king safety more diligently than white. That gives white an edge in developing his pieces in the opening. In Even Chess, that edge is countered by the rule that black, but not white, may castle out of check or move the black king over a square attacked by white. That gives black more latitude to counter white's development in the opening, and it opens new territory for opening lines to be explored.

Do the rules make Even Chess an equal game? That can be debated and tested. Moving first is also an advantage in terms of capturing material, because when white captures a piece, black has one less piece with which to capture a white piece on the same move. However, the rules may be adequate to compensate black for that advantage.
« Last Edit: April 23, 2018, 07:36:47 pm by Steve Brown »

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John_Lewis

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Re: Even Chess
« Reply #1 on: April 23, 2018, 06:34:09 pm »
King's Capture rules are not new, but this is the first time I have seen Black given the chance to move an extra turn at the end of the game as a way to reduce the first move advantage.

Further, the right to castle out of check or through check dynamically changes how the game is played and is interesting in its own right... does it result in parity for black and white.

I find the ideas both fascinating. However I fear they will not compensate for White's initiative with their first move.

Perhaps restrict White so that their first move may NOT be a two space pawn move? With this addition you might reach parity. However you'd need a computer to test by playing millions of games.

Steve Brown

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Re: Even Chess
« Reply #2 on: April 23, 2018, 07:56:27 pm »
King's Capture rules are not new, but this is the first time I have seen Black given the chance to move an extra turn at the end of the game as a way to reduce the first move advantage.

Of course, black's guaranteed final move is "extra" only in the sense of equalizing the number of moves for white and black.


I find the ideas both fascinating. However I fear they will not compensate for White's initiative with their first move.

I thought of naming the variant "Equal Chess," but the goal is not absolute parity but to give black more latitude to develop aggressively and more incentive to counterattack.

Perhaps restrict White so that their first move may NOT be a two space pawn move? With this addition you might reach parity. However you'd need a computer to test by playing millions of games.

Adding that to the existing rules could hand black an advantage,  ;D
but that could be a rule in a different variant.
« Last Edit: April 23, 2018, 07:58:26 pm by Steve Brown »

John_Lewis

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Re: Even Chess
« Reply #3 on: April 23, 2018, 09:37:56 pm »

Perhaps restrict White so that their first move may NOT be a two space pawn move? With this addition you might reach parity. However you'd need a computer to test by playing millions of games.

Adding that to the existing rules could hand black an advantage,  ;D
but that could be a rule in a different variant.

Then maybe that's the only rule you need... again, you'd need to test with something like LeelaZero.

Steve Brown

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Re: Even Chess
« Reply #4 on: April 24, 2018, 12:52:25 pm »
Then maybe that's the only rule you need... again, you'd need to test with something like LeelaZero.

Restricting white's first pawn move to a one-square move is a radical departure from orthodox chess in the opening phase of the game. The intent of Even Chess is to be like orthodox chess, but more even, not necessarily an equal game. Feel free to create a variant with any rules and any name you like.  You would need a computer to play millions of games to ascertain if equality is attained.

Steve Brown

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Re: Even Chess
« Reply #5 on: April 24, 2018, 01:15:15 pm »
The Rules of Even Chess

1. The rules of orthodox chess apply, except as modified by the following rules.

2. The object of the game is to capture the opponent's king. The game ends when one or both kings have been captured, and both players have made the same number of moves.
If one king is captured, the winner is the player whose king is still on the board. If both kings are captured, the result of the game is a draw.

3. When a player's king is in check, the player is not required to get out of check and may make any move, including one that attacks or captures the opponent's king.

4. A player may move his king into check and may use his king to attack or capture the opponent's king.

5. Black, but not white, may castle out of check or, while castling, move his king over a square attacked by a white piece.

« Last Edit: April 24, 2018, 02:04:01 pm by Steve Brown »

Greg Strong

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Re: Even Chess
« Reply #6 on: April 24, 2018, 11:14:46 pm »
This is an interesting idea.  As far as I know, this approach to mitigate white's first move advantage is new.

Unfortunately, playing for king capture removes stalemate from the game.  Stalemate is nice because it gives the losing player something to play for.

You could, instead, address it like this...  If white inflicts checkmate, black may make one more move if and only if it results in checkmating white.  In this case the game is a draw.

Steve Brown

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Re: Even Chess
« Reply #7 on: April 25, 2018, 01:43:22 pm »
This is an interesting idea.  As far as I know, this approach to mitigate white's first move advantage is new.

Unfortunately, playing for king capture removes stalemate from the game.  Stalemate is nice because it gives the losing player something to play for.

You could, instead, address it like this...  If white inflicts checkmate, black may make one more move if and only if it results in checkmating white.  In this case the game is a draw.

Now it gets complicated. In orthodox chess, the purpose of the rules regarding check and checkmate is to ensure a "proper" end to the game, where one player inflicts on the other the condition in which he cannot get his king out of check, a condition in which the king cannot avoid being captured if that were a legal move. Under those rules, a player cannot blunder into a loss by leaving his king en prise, because doing so would be an illegal move. Therefore, it is illegal for a player to leave his king in check or to move it into check, raising the possibility of stalemate, a condition in which a player has no legal move. With careful play, stalemate can be avoided, so stalemating the opponent is a blunder. Ironically, if capturing the king were the object of the game, the condition known as stalemate would be zugzwang, in which a player would have no better move than to expose his king to attack. In that case, stalemate is not a blunder but a desirable condition to inflict on the opponent. So while the rules of check and checkmate are to prevent a player blundering his king away, those same rules make it possible for a player who has a winning position to blunder into a draw. In my view, the zugzwang interpretation is more logical than the stalemate interpretation of the position in which a player has no legal move.

You proposed the rule "If white inflicts checkmate, black may make one more move if and only if it results in checkmating white. In this case the game is a draw." The problem with that rule is that it does not allow black to respond to checkmate by putting the white king in check. Under the existing rules of Even Chess, black doing that leaves white with two options:

1. White captures the black king, black captures the white king, and the game is a draw.

2. White gets his king out of check, leaving the black king in checkmate.

After option #2, black can still check the white king. Theoretically, the game could go on for several more moves while black is in a checkmated position, by continuing to put the white king in check. At some point, black runs out of checks, in which case he loses on the next move when white captures his king and black cannot capture the white king, or he succeeds in checkmating the white king. In the latter case, white captures the black king on the next move, black captures the white king, and the game is a draw.

Still, stalemate can be preserved in Even Chess by adding a somewhat arbitrary rule:

6. If a player whose king is not in check cannot move without putting his king in check, the game is a draw.

As I wrote in the first paragraph above, I believe the zugzwang interpretation of the stalemate position is more logical, and it is consistent with rule #4, that a player may move his king into check. However, in the spirit of collaboration, I leave it up to members of this forum to decide whether to add proposed rule #6 to the rules of Even Chess. Another possibility is that rule #6 could be optional. Eventually, the majority opinion will be respected.



« Last Edit: April 25, 2018, 07:23:22 pm by Steve Brown »