[Retros] 50-moves rule and mate

[Rol, Guus]

Hi Andrew,

I wrote my original analysis under the assumption (call it delusion) that the 50-moves rule was automatic. Since I can find no confirmation for this in source material I need a rethink on the whole subject. Having optional and preemptive claims complicates matters considerably but the ordering of evaluation rules, whether by claim or by automation, is always a relevant issue indeed.

Guus Rol.



> -----Oorspronkelijk bericht-----

> Van: retros-bounces at janko.at [mailto:retros-bounces at janko.at] 

> Namens andrew buchanan

> Verzonden: dinsdag 16 januari 2007 16:59

> Aan: 'The Retrograde Analysis Mailing List'; pastmaker at aol.com

> Onderwerp: Re: [Retros] 50-moves rule and mate

> 

> 

> Hi Tom,

> 

> Thanks for your interesting mail. You wrote:

> 

> >under the FIDE rules for over-the-board play only the player on the 

> >move can claim a draw.  The checkmating move is unassailable 

> under that 

> >regime because the other player (i) is not on the move when the 

> >checkmating move is played, and so must remain mute while 

> the move is 

> >played, and (ii) never regains the move, as the play of the 

> checkmating 

> >move ends the game.

> 

> I agree with your conclusion that # trumps 50M (if it's the 

> mated player who wants to claim), but I disagree with how you 

> reach that conclusion.

> 

> In order to know that it is #, you have to examine the new 

> position, according to Art 1.2 ("The objective of each player 

> is to place the opponent's king 'under attack' in such a way 

> that the opponent has no legal move which would avoid the 

> 'capture' of the king on the following move.") 

> 

> In this position, the possibly checkmated player already has 

> the move. Firstly, because Art 1.1 says he does ("A player is 

> said to 'have the move', when his opponent's move has been 

> made.") Secondly, because in the new position you can't 

> verify the legal moves correctly unless the right player has 

> been assigned the move. Thirdly, note the use of the present 

> tense in Art 1.2.

> 

> Surely Guert Gijssen at Chess Café must have answered this 

> question before? It's not really something we problemists 

> should have to guess.

> 

> Notes:

> 

> (1) My reading is that stalemate and dead position are 

> checked for at the same time as checkmate... just after the 

> player has acquired the move, but before the new player can 

> do anything.

> 

> (2) I think Draw by Repetition is handled in the same way as 

> 50M, and if it mattered (which I don't think it ever can in 

> the game of chess because the situations are mutually 

> exclusive) would be trumped by mate/pat/death.

> 

> (3) But we've really only handled half of it. We were 

> assuming that it was the mated player who wanted to claim the 

> draw. In the weird world of composition, it could easily be 

> the mating player who wants to claim the draw, in which case 

> if we look at the Laws of the Game again, it is 50M which trumps #.

> 

> (4) Now how does that affect chess compositions? The Codex 

> doesn't give me adequate support to answer that question.

> 

> The key point is that in the game, depending on who does the 

> claiming, 50M or # may prevail. For this reason, it will not 

> be so easy for Guus to craft a similar convention for 50M 

> which worked to some extent for Rep.

> 

> Regards,

> Andrew.

> 

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