or rook in practical play is rare, and promotion to bishop is even rarer, but they are a popular theme in composed chess problems, such as the Saavedra position. For example, a study by Jan Rusinek sees White promoting to knight, bishop and rook in order to induce stalemate. An Allumwandlung is a problem where promotions to all four possible pieces occur. An extreme example is the Babson task, a where promotions by Black must be countered by matching promotions by White (so if Black promotes to a rook, so does White, and so on). Promotion to a knight In the diagrammed position, 1...d1=Q? leaves material equal and leads to a drawn position. Instead, promotion to a knight with 1...d1=N+! wins by virtue of a fork: 2.K(any) followed by 2...Nxb2 leaves Black a piece up with a winning endgame. Promotion to knight may also be done for defensive reasons. For example, a knight promotion is a standard defensive technique in a rook versus pawn endgame; a 2006 game between Gata Kamsky and Étienne Bacrot shows such a case. White threatens to capture the pawn or checkmate by Rh1 if the black pawn promotes to a queen, rook, or bishop. The only move that does not lose for Black is 74... e1=N+! The resulting rook versus knight endgame is a theoretical draw (see pawnless chess endgame). In the actual game, mistakes were made in the rook versus knight endgame, and White won on move 103. Zurakhov–Koblencs is a very rare example of a game with two significant promotions to knights; it also features a rare instance of a non-checking knight promotion. In the first diagram, Black threatens 57...Nxg7, and if White avoided this by promoting to queen, rook, or bishop, Black would reach a drawn position with 57...Ne7+! and 58...Nxg8. The only winning move is 57. g8=N!, which White played. Twenty-one moves later, the players reached the position in the second diagram. Once again, a promotion to anything other than a knight would allow a knight fork, e.g. 79.c8=Q?? Nd6+ and 80...Nxc8, with a drawn ending. White instead played 79. c8=N+! (Here, there are other winning moves, such as 79.Kc5.) 79... Kb8 80. Kb6 and Black resigned, since White cannot be stopped from promoting a third pawn, this time to a queen. Promotion to a rook In the diagrammed position, Black threatens to capture White's pawn and draw the game. Promotion