Chess Article #53: The Chess endgame: The Cochrane Defense Adapted and Condensed from Wikipedia, the Free Encyclopedia The Cochrane Defense is a method for drawing in the chess endgame with a rook versus a rook and bishop. It was discovered by John Cochrane. This combination of material is one of the most common pawnless chess endgames. Many of the longest chess games on record have this combination of material since at one time the fifty-move rule which would make the game a draw after fifty moves with no capture was extended to one-hundred moves for this combination of material. For example, the longest tournament game on record is a 269-move game by Ivan Nikolic and International Master Goran Arsovic. The last 103 moves of this game had this material and ended in a draw. Accurate play is required for the defense. The defense is most effective near the center of the board, and doesn't work on the edge (Nunn 2007:174ff). The Cochrane Defense works when: * the defending rook pins the bishop to the king on one of the four central files (c through f) or ranks (3 through 6), and * there are two or more ranks or files (respectively) between the kings (de la Villa 2008:213-16). Details Diagram #1: White: King at e5, Rook at a7, Bishop at e4 Black: King at e8, Rook at e2 Budnikov-Novik, 1991 Cochrane defense. Black to move, draw with either side to move. The defense is most effective near the center of the board. In this position, if the pieces on the e-file were moved to the f-file, then if 1. Ke5 the response 1. ... Kg8, puts the black king dangerously close to the corner (Nunn 2007:161ff). The defense does not work on the edge of the board. In this position (Diagram #1) from a 1991 game between Alexandar Budnikov and Maxim Novik, White would like to get his king to d6 and bishop to d5, to win by a method of Philidor (see Philidor position; Rook and bishop versus rook, Chess Article #52#) - however the pin of the bishop to the king prevents it. If White plays 1. Kd5 or 1. Kf5 then Black moves his king in the opposite direction, so if the bishop then moves, the black rook cuts off the white king. There is another drawing method in positions with this set of material, called the "second rank" defense (with the king and rook both on a rank or file next to the edge of the board). However, the Cochrane Defense is more popular among grandmasters (Nunn 2002:174ff). There are some key ideas for the defender to observe: * wait by moving the rook between e1 and e2 * answer Kd5 with ... Kf8 and Kf5 by ... Kd8 * drive the rook away from the seventh rank at the first opportunity * move the king away from the eighth rank, as near the center of the board as possible * once the king has left the back rank, hold off the attacking king for a few moves * when the white king gets back to the fifth rank (or equivalent in other directions), switch the rook around and head for the Cochrane position again (perhaps rotated 90 or 180 degrees). This phase is important because the opposing king must not be allowed to reach the sixth rank (or equivalent). The game continued: 1. ... Re1 2. Kd5 Kf8! 3. Bf5 Re7! 4. Ra8+ Kf7 5. Ra1 Kf6 6. Bc8 Re5+ 7. Kd6 Re2 8. Rf1+ Kg5 9. Bb7 Re3 10. Kd5 Re2 11. Kd4 Re7 12. Bd5 Re8 13. Rf7 Rb8 14. Ke5 Rb5 and the position is back to the basic Cochrane position, rotated 90 degrees, and the fifty-move rule is closer to coming into effect. The Budnikov-Novik game continued, with the Cochrane position being reached again. Eventually a draw was claimed by the fifty-move rule (Howell 1997:145-47).========== The blind-chess mailing list View list information and change your settings: //www.freelists.org/list/blind-chess List archives: //www.freelists.org/archives/blind-chess =========