Evil puzzle

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Jesper Norgaard
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Re: Evil puzzle

Post by Jesper Norgaard » Sun Apr 15, 2018 2:53 pm

Kevin Williamson wrote:
Sun Apr 15, 2018 2:14 am
Jesper Norgaard wrote:
Sun Apr 15, 2018 12:51 am
Kevin Williamson wrote:
Sat Apr 14, 2018 9:11 pm
I'm not sure that I've understood the 'rules' but how about 1.c4 e6 2. e3 Kc2. Assuming that 3.Qxc2 is illegal because you can't take a king, then there appear to be six moves (Qe2, Qf3, Qg4, Qh5, Bd3, Ne2) which don't result in checkmate and another twenty which do.
I get 19 moves that are checkmate:
a3 a4 b3 b4 c5 Na3 Nc3 d3 d4 e4 Be2 Nf3 Nh3 f3 f4 g3 g4 h3 h4
Don't forget 3.Ke2, so I think it is 20.
Of course, you are right ... slapping my forehead ... so only 1.c4 e6 2.Nf3 Kc2 is better with 21 checkmate moves. I wonder how much it can be increased by allowing more moves? When I made the puzzle, I could have made it "White moves and forces Black to checkmate him in 1 move!" with 1.Kxc7.

Just a warning, don't try to pull a fast one with 1.Kxc7 even if you are 1.5 points ahead before the last round, not only can Black insist on a legal move instead of 1.Kxc7 (not a problem), but more likely the arbiter will disqualify White for unsportsmanlike behavior. Are there any arbiter opinions about this?

Stewart Reuben
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Re: Evil puzzle

Post by Stewart Reuben » Sun Apr 15, 2018 3:21 pm

I raised the problem many years ago about the finl move legally givig checkmate, but an earlier move being illegal.
A good example was in blitz. 1 e4 e5 2 Nf3 Nc6 3 Bc4 Nf6 4 Q before White could complete Qe2 and press the clock , Black plays Nd4 although it is not yet his move. So White plays 4 Qh5 (illegal) but Black has forfeited his right to claim. The game becomes 4 Qh5 Nd4 5 Qxf7 mate.

Nobody ever came up with a way of solving this problem and expressing it in the Laws. So we accepted the problem as insoluble so that the arbiter has to rely on 'bringing the game into disrepute'. Jesper, your absurd allegation, >FIDE loves absurd checkmates, and will go to their grave defending them. I think these checkmates should be abolished.< Why not write the rule correctly? Now is the perfect opportu nity. We are meeting about revising the Laws later this week.

Just as this 'problem', putting the Black king on c2, totally illegally, and pretending the current position is not already chackmate, brings problem composing into disrepute.

Nick Ivell
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Re: Evil puzzle

Post by Nick Ivell » Sun Apr 15, 2018 4:14 pm

Personally I've no interest in this kind of 'problem' relying on illegal moves. This is chess, not draughts or Go.

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Jesper Norgaard
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Re: Evil puzzle

Post by Jesper Norgaard » Sun Apr 15, 2018 5:33 pm

The relevant article is 5.1.1:
"The game is won by the player who has checkmated his opponent’s king. This immediately ends the game, provided that the move producing the checkmate position was in accordance with Article 3 and Articles 4.2 – 4.7."

Geurt Gijssen suggested that to be a valid checkmate, all moves of the game should have been legal, which met fierce resistance and was turned down. However it is not necessary to go that far to mend the situation. If the last move of each player was legal, the checkmate is valid, and we would eliminate absurd checkmates like 1.e3 f5 2.Bb5 d5(+) 3.Qh5# because even though 3.Qh5 is a legal move, 2...d5 is not since it exposes the king to check. Also it will enforce that 1.Kxc7 Nf6# is not a valid checkmate.

This is the suggestion:
"The game is won by the player who has checkmated his opponent’s king. This immediately ends the game, provided that the last move of each player producing the checkmate position was in accordance with Article 3 and Articles 4.2 – 4.7."

I don't think many arbiters would object to this article change. Probably most players wouldn't even notice it. In my humble opinion it mends a gaping hole in the current Laws of Chess.

Grammar:
I am assuming that you can say A was fine, and B was fine, you don't need to say A and B were fine. In other words, each move was legal referring to several moves. For instance, to produce a legal position, you must ensure that each move was legal of all the preceding moves.

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Jesper Norgaard
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Re: Evil puzzle

Post by Jesper Norgaard » Mon Apr 16, 2018 10:46 pm

This is the suggestion:
"The game is won by the player who has checkmated his opponent’s king. This immediately ends the game, provided that the last move of each player producing the checkmate position was in accordance with Article 3 and Articles 4.2 – 4.7."

There is a couple of problems with this suggestion. The first is rather technical in nature. Article 3 is the legality of the move, and Articles 4.2-4.7 covers touch-move rules. In reality the checkmating move needs to comply with both, but the move immediately before only needs to comply with legality, not touch-move rules. In fact a player checkmated can now claim that since he had touched another piece first before moving his last move, he should be allowed to change his move to be with the first piece touched, to avoid the checkmate that happened to him. That doesn't feel right.

The other problem is that this needs to cover Rapid and Blitz chess as well. And with the above we have set up the framework to correct the illegal move that preceded the checkmating move. But in A.4.2 it says "If the opponent does not claim and the arbiter
does not intervene, the illegal move shall stand and the game shall continue." So we can't fix the error because only the last move can be fixed.

To me the Article 7.5.1 has always been the pinnacle of correcting all illegal moves. It has never appeared sensible to me to restrict this as it is done in A.4.2, to cover only the last move. This was the reason we have a Blitz game including an illegal move (Carlsen-Inarkiev) which could not be mended even though the problem was obvious to both players about Inarkiev's move, giving a check when he himself was in check, and thus instead of correcting it the arbiters could only offer to continue the game with the illegal move included. It's a disgrace quite frankly.

I think we need to rely on the players to report which illegal moves have been detected, and let the arbiter correct them, even in Blitz and Rapid, no matter how many moves have passed. As long as the two players are honest and accurate in reporting what happened, a solution can be found as outlined in 7.5.1 :"If the position immediately before the irregularity cannot be determined, the game shall continue from the last identifiable position prior to the irregularity." A solution can always be found using this philosophy. Yes it is harder in Blitz, without score sheets. But the consequences of letting illegal moves stand are horrific, we are insisting on staining the history of chess with unplayable games like Carlsen-Inarkiev. It stopped abruptly because Inarkiev refused to continue, but otherwise we could not have played through the game in any program that is checking the moves for legality. That is why they should be corrected. It is a price that is worth to pay, to keep the moves legal.

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