Thursday, March 6, 2008

How much is enough?

A moderately obscure rule which has come up a few times recently is that of insufficient material. This is really two different questions – insufficient material to continue the game, and insufficient material to win on time.

Insufficient material to continue the game is fairly straightforward. If the position is such that neither player can checkmate by any possible sequence of legal moves, the game is immediately drawn. The obvious example of this is King versus King, but it also covers things like a King and pawn ending with a locked pawn chain preventing either side from penetrating. The FIDE rule says just that (“… neither player can checkmate the opponent’s King with any series of legal moves”). The USCF rule also says this in 14D4, but for reasons which escape me it specifies King versus King (14D1), King and minor piece versus King (14D2), and King and Bishop versus King and Bishop of the same color (14D3). These are obviously redundant, unless perhaps the author feared that some of his readers would not realize that they couldn’t checkmate with a Knight.

Insufficient material to win on time is a bit more complicated. Here the FIDE and USCF rules differ significantly. The FIDE rule says that the game is drawn if the player whose flag falls “cannot checkmate (the opponent’s) King by any by any possible series of legal moves, even with the most unskilled counterplay.” This is simple and easy to understand, but has the drawback that a player might be worse off for having more material. Consider, for example, King and Queen versus King and Knight. If White’s flag falls, the game is drawn, since there is no possible way to construct a checkmate for Black. But give White an extra Rook and two pawns, and he could lose on time under the FIDE rule.

The USCF rule is longer. Whether it’s better is a good question. It specifies three cases in which a player may not win on time: 1) lone King, 2) King and minor piece and the player “does not have a forced win,” and 3) King and two Knights, opponent has no pawns, and – again – the player “does not have a forced win.” Now, this wording was clearly intended to disallow “helpmates,” and it does accomplish that – but it creates other difficulties. In the first place, it’s not entirely logical, since it’s hard to argue that it would take worse play to lose with Queen, Rook and two pawns versus lone Knight than with Queen versus a blocked pawn on the second rank. The other problem is the “forced win” clause. It’s necessary in order to deal with positions like the one in the diagram, as otherwise Black could make a draw by refusing to move. But it brings back the nasty specter of TD adjudication, which should have no place in serious chess.

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