Saturday, March 16, 2013

More Elementary Endgames

It was a pretty tame opening to the London Candidates event. There were 4 draws with none of the players seemingly willing to risk much early on in the tournament. The game between Ivanchuk and Grischuk did give me a chance to explain the square of the pawn to some students today. One of the kids asked me why they had agreed to a draw, so we had a look at the endgame.

It is white to move and it looks like black's 2 queen side passed pawns give him an advantage. However, white's king can block those pawns if it heads to the queen side (rather than trying to win the h-pawn which was what some of the kids thought of straight are so materialistic!). Basically, a quick calculation can be made based on making a square which has where the pawn currently stands (b5) and where it wants to get to (b1) as one side. The other corners of the the square ill be f5 and f1. The golden rule here is that white's king must be able to enter this square if it wants to prevent the pawn from promoting. So white could play 1.Kf4 here, and still be able to get into the square of the pawn after 1..b4 2.Ke4 b3 3.Kd3 b2 4.Kc2 b1=Q 5.Kxb1.

Ivanchuk wasted no time in heading off the pawns, playing 1.Ke4 and after 1..a5, he started on creating his own passed pawns on the king side with 2.f3. They played 2..a4 3.Kd3 Getting inside the square of the a-pawn (a4, a1, d4, d1), 3..a3 and a draw was agreed!

So why was a draw agreed here? White must enter the square of the pawn now, so 4.Kc2 seems reasonable. The thing is, black can't stop white from advancing pawns on the king side, so perhaps the game might continue 4..b4 5.g4 hxg4 6.fxg4 when we have a position where neither side can make progress.

White's king must stay close to the black pawns, but black's king can't leave the white pawns to advance. But neither side can advance their pawns far as the kings will block them. Notice that a king that sits between the pawns, such as a white king on b3, cannot take the backward of the 2 pawns as that would leave the other pawn to promote. So neither side can make progress.

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