28 December 2012

A Rook Endgame

In a three minute blitz game on a website, my opponent blundered from the diagram position. Even so, another two dozen moves were needed to provoke his resignation.

Black to move

36...Kf4?? 37.Rxf6+ and White has a clear advantage.

After the initial rush of self-praise for outplaying my opponent in a rook endgame subsided, I began to seek the truth of the position.

Black should have played 36...Kg6. Then, White remains down a pawn. But, does Black have an appreciable advantage? I downloaded the game from the website and played the position against tChess Pro on the iPad. Twenty moves later, we were down to kings and rooks--a dead draw.

36...Kg6 37.a5 Re8

White to move

Stockfish 2.3 regards this move as second best, but judges it and the preferred 38.Kxc5 as equal.

38...e4 39.fxe4 Rxe4+ 40.Kxc5 Rxg4 41.Kb5 Rg2 42.Rc4 Rb2+ 43.Rb4 Ra2 44.Ra4 Re2 45.a6 Re8 46.a7

Black to move

46...Kf5 is interesting. 47.a8Q Rxa8 48.Rxa8 and Black's two pawns are equal to White's rook.

47.Kc4 g4 48.Kd3 f5 49.Ke2 Kg5 50.Kf2 f4

White to move

51.Kg2 Kf5 52.Kf2 Ke5 53.Kg2 Ke6 54.Rxf4 Rxa7 55.Rxg4 1/2-1/2.

Stockfish finds no substantive errors in the play of the human, nor of tChess Pro's engine. With correct play, neither side had an advantage. 36...Kf4 was a game losing blunder in a position that should have been drawn.

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