[Retros] 50-moves rule and mate

[andrew buchanan]

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.