Saturday 5 May 2012

The Single Bishop Mate

The diagrammed position comes from the detective novel "The Bishop Murder Case" by S.S Van Dine. In the position it is Black to play and mate. Now apart from its literary interest, it may also have a legal one.
Over the years there have been various proposals to eliminate wins on time that rely on 'trick' mates, ie checkmates that require the suicidal co-operation of the opponent. One idea is to only allow mates than can be forced without the help of your opponents pieces or pawns (ie KQ or KR are good, but KB or KN are out).
So going back to the diagram. After 1. ... Nxc2 2.Kxc2 b1=Q+ 3.Kxb1 should White be able to claim a draw here, or suffer the supposed injustice of 3. ... Kd3 4.Ka1 Kc2 5.d3 Bb2#?

3 comments:

Anonymous said...

The problem with such proposals as always, is where to draw the line. If a draw can be claimed because one side can clearly not force mate, but must rely on an opponent's mistake ('suicide') then why not apply it to any position? However that would require analysis to demonstrate the claim or rebuttal. Then you go down the slippery slope of who is qualified, or strong enough, to provide or confirm the analysis and that may lead to discussion of whether a weaker player would have been capable of finding the win/draw. I played in a rapid tournament years ago in the USA where the rule was that a player short of time could claim a draw in a position "that a novice player could draw against a grandmaster". I successfully claimed in a position of R+3P v R+3P, which, looking back, had plenty of room for a novice to go wrong. Better to keep the rules as simple and black and white as possible. If a mate is legally possible, you lose, if not you draw. MP

Anonymous said...

the problem with your reasoning is that in most cases it is not a question of finding a draw but much rather being stupid enough to find a (self)mate.... eg.with K on h1 and pawn on a2 vs K+knight I can still lose if I am stupid enough to set up the only selfmating setup with K on a8 and pawn on a7. Declaring these positions anything else but a draw is plain stupidity in my opinion, and I actually don't know what the rules say.
Stretching this even further, following these arguments 2knights vs king should also win then if the defender runs out of time, as mate is possible...

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