10 June, 2009

A fantastic idea

Eliminating stalemate by eliminating check:

In chess, one way a game can be declared a draw is if black, say, has no legal move. This is called stalemate. Typically stalemate occurs because white has a material advantage but fails to checkmate and instead leaves the black king with no space to move that does not walk into check. It is illegal to place your own king in check.

The reason stalemate is an artificial rule is that check is an artificial rule. Clearly the object in chess is to conquer the opponent’s king. One can imagine that check evolved as a way to prevent dishonorable defeat when you overlook a threat against your king and allow it to be captured even though it could have escaped. To prevent this, if your king is in check the rules of chess require that you escape from check on the next move and it is illegal to move into check. This rule means that the only way to win is to checkmate: place your opponent in a position where his king is threatened and cannot escape the threat. The game ends there because on the very next move the king will certainly be captured.

This gives rise to stalemate: it is only because of check that a player can have no legal move. If we dispensed with checkmate, replacing it with the more transparent and natural objective of capturing the king, and eliminating the requirement that you cannot end your turn in check, then a player would always have a legal move. (it is easy to prove this.) Thus, no stalemate.


Elliot said...

i have never thought much about the rationale for a "check" rule. interesting idea. one response is that, especially among newer players, the check rule forces more games to be played out in a more strategically demanding way, by doing away with an unexpected capture of an enemy king. on the other hand, perhaps beginners would sooner learn to pay closer attention if they could lose their king without warning.

another argument against this position is that forcing an attacking player to take into account the possibility of stalemate is a strategically worthwhile or interesting thing in itself. i'm not sure that's true, but it does add a wrinkle to the endgame.

i will say, though, that there is no such thing as an "un-artificial" rule. at least not in chess; all rules are artificial constructions. thus its not enough to argue for a repeal of the check rule on the grounds of artificiality alone; one must go further to make the case that the overall game (based on a criteria that you must in turn define) is better off without that rule. not sure senor blogger has done that.

spencer said...

I guess one way to rephrase the artificiality point is in terms of Occam's Razor. Do not multiply rules unnecessarily! It's not really necessary since it won't affect the game when both players are careful. The game would be more concise and elegant without it.

In any case, perhaps this requires some playtesting...