Larry Evans'
Endgame Quiz

Introduction.
[Welcome to Larry Evans' Endgame Quiz. This quiz contains 50 multiple choice questions that are designed to determine your overall endgame strength. You will be asked to choose which move is the best one in a given position, and after selecting an answer you will be told if your answer was correct or not (and why). After going through the 50 questions in this manner, you will be given your endgame rating based on your score.
It is required that you complete the entire quiz in one session, and completing the quiz will take approximately one to two hours, depending on your level of play. 

Good Luck!

GM Larry Evans
]

1.
[{F:W}
{B:8/5p2/1p6/1P2K2k/8/8/8/8 WHITE}
{QM:Composed by Grigoriev. White to play and draw.; Kd5:Incorrect. This is a good example of how moves can be eliminated simply by making a mathematical count. Too slow is 1 Kd5? f5 2 Kc6 f4 3 Kxb6 f3 4 Kc7 f2 5 b6 f1/Q 6 b7 Qc4+ 7 Kd8 Qb5 8 Kc7 Qc5+ 9 Kd8 Qd6+ 10 Kc8 Qc6+ 11 Kb8 Kg5 and Black keeps repeating the process until his king closes in for the kill.:0; Kf5:Correct. Both sides must play sharply. Correct is 1 Kf5! Kh4 2 Kf4 Kh3 3 Kf3 Kh2 4 Kf2 f6 5 Kf3 Kg1 6 Ke4! Kf2! (not 6...Kg2? 7 Kf5 wins for White) 7 Kd5! f5 8 Kc6 and both sides queen, leading to a draw.:10; Kf6:Incorrect. Going directly after the pawn loses after 1 Kf6? Kg4 2 Kxf7 Kf5 3 Ke7 Ke5 4 Kd7 Kd5 5 Kc7 Kc5.:0}]

2.
[{F:W}
{B:8/6pp/8/4kPPP/8/8/2K5/8 WHITE}
{QM:Composed by Fahrni. White to play and win.; g6:Incorrect. White actually loses after 1 g6? h6 2 Kd3 Kxf5:0; h6:Incorrect. White only draws after 1 h6? gxh6 2 g6 hxg6 3 fxg6 Kf6 4 Kd3.:0; f6:Correct. The only way to create a passed pawn that can’t be stopped is 1 f6! gxf6 2 g6! hxg6 3 h6!:10}]

3.
[{F:W}
{B:8/6pp/5p2/3k1PP1/5K1P/8/8/8 WHITE}
{QM:Chigorin-Tarrasch, Ostend 1905. White to play and draw; Kg4:Correct. Never give up the ship! In the game White did -- a rare case of premature resignation. He overlooked a miracle draw by 1 Kg4! Ke5 2 g6! h6 (if 2...hxg6 3 fxg6 f5+ 4 Kg5 f4 5 h5 f3 6 h6 gxh6+ 7 Kxh6 f2 8 g7 and both sides queen) 3 Kh5 Kxf5 stalemate!:10; g6:Incorrect. Hopeless is 1 g6? h5! 2 Kf3 Ke5 and Black grazes on pawns for dessert.:0; h5:Incorrect. Equally futile is 1 h5? h6 2 gxh6 gxh6 3 Kf3 Ke5 4 Kg4 Ke4 5 Kg3 Kxf5 mopping up.:0}]

4.
[{F:W}
{B:8/6p1/6k1/8/1pP4p/8/P4P2/5K2 WHITE}
{QM:Radoicic-Cvetkovic, Yugoslavia 1999. White to play and draw; Kg2:Incorrect. White lost by 1 Kg2? Kf5 2 c5 g5! 3 Kh3 Ke5 4 c6 (no better is 4 f4+ gxf4 5 Kxh4 Kd5 6 Kg4 Kxc5 7 Kxf4 Kd4 8 Kf3 Kc3) Kd6 5 c7 Kxc7 6 f4 gxf4 7 Kxh4 Kd6 8 Kg4  Ke5.:0; c5:Correct. The drawing resource is 1 c5! Kf5 2 f4! (to stop g5 once and for all) Ke6 3 Kg2 Kd5 4 Kh3 Kxc5 5 Kxh4 Kd4 6 Kg5 Kc3 7 Kg6 Kb2 8 Kxg7 Kxa2 9 f5 b3.:10; f3:Incorrect. The pointless 1 f3? loses a vital tempo and the game.:0}]

5.
[{F:W}
{B:1k6/3p4/1P6/1K6/8/8/1P6/8 WHITE}
{QM:Composed by Grigoriev. White to play and win; Ka6:Correct. It’s necessary to force Black to push his d-pawn by triangulation. 1 Ka6! d6! (The best defense. If 1...d5 2 Kb5 Kb7 3 Kc5 d4 4 Kxd4 Kxb6 5 Kc4 Kc6 6 Kb4 Kb6 7 b3 gains the opposition) 2 Ka5! (The only way -- not 2 b7? d5 3 Kb5 Kxb7 4 Kc5 Ka6! holds. Or 2 Kb5? Kb7 3 Ka5 d5 4 Kb5 d4) Ka8 3 Kb4 Kb8 4 Ka4 Ka8 5 Ka5 Kb8 6 Ka6 d5 7 Kb5 wins.:10; Kc5:Incorrect. The tempting 1 Kc5? Kb7 2 b3 Ka6 3 b4 Kb7 4 Kb5 d5 5 Kc5 d4 6 Kxd4 Kxb6 7 Kc4 Kc6 draws because White pushed his last pawn too soon:0; b3:Incorrect. Wrong is 1 b3? Kb7 2 Kc5 d6+ 3 Kb5 d5 4 Kc5 d4 5 Kxd4 Kxb6 6 Kc4 Kc6 7 Kb4 Kb6 and Black holds the opposition because White no longer can gain a tempo by b3.:0}]

6.
[{F:W}
{B:k7/2p5/8/KP3p2/8/8/6P1/8 WHITE}
{QM:Composed by Grigoriev. White to play and win; b6:Incorrect. 1 b6? Kb7! 2 bxc7 Kxc7 leads to nought.:0; Kb4:Incorrect. Insufficient is 1 Kb4? Kb7 2 Kc5 f4 3 Kd4 Kb6 4 Ke4 Kxb5 5 Kxf4 c5 6 g4 Kc6 7 g5 Kd6, and the position is equal:0; Ka6:Correct. The right way to win is 1 Ka6! Kb8 (if 1...f4 2 b6! c6 3 b7+ Kb8 4 Kb6 c5 5 Kxc5 Kxb7 6 Kd5 wins) 2 g3! Ka8 (no better is 2...Kc8 3 Ka7 Kd8 4 Kb8! Kd7 5 Kb7 Kd8 6 Kc6 Kc8 7 Kd5 Kb7 8 Ke5 Kb6 9 Kxf4 Kxb5 10 g4 c5 11 g5 c4 12 Ke4!) 3 b6 Kb8 4 Kb5! Kb7 5 bxc7 Kxc7 6 Kc5 Kd8 7 Kd6! wins (but not 7 Kd4? f4!).:10}]

7.
[{F:W}
{B:8/8/1p1p3p/3P4/4K3/8/4P2k/8 WHITE}
{QM:Composed by Herbstmann. White to play and win; Kf3:Correct. Despite a material deficit, White can force an amazing win by 1 Kf3! b5 2 e4 b4 3 Ke2! b3 4 Kd1! Kg3 5 e5 dxe5 6 d6 e4 7 d7 e3 (if White had moved his king to d2 on move 4, this push would be accompanied by check with a draw after 8 Kxe3 b2) 8 d8/Q and wins.:10; Kf5:Incorrect. Not 1 Kf5? b5 2 e4 b4 3 e5 b3 4 exd6 b2 5 d7 b1/Q queening with check!:0; Kd4:Incorrect. White perishes after 1 Kd4? Kg3 2 e4 Kf4.:0}]

8.
[{F:W}
{B:8/7p/6p1/5p2/1k3P1P/6P1/8/5K2 WHITE}
{QM:Riga Society-Polytechnic School, Riga 1892. White to play and draw; Kg2:Correct. White is in peril because his king is so passive, yet he can draw by 1 Kg2! Kc4 (useless is 1...h5 2 Kf2! keeping the opposition) 2 h5! gxh5 3 Kh3 Kd4 4 Kh4 Ke4 5 Kxh5 Kf3 6 Kg5 Kxg3 7 Kxf5.:10; Ke2:Incorrect. Trying to keep Black’s king from penetrating is futile. 1 Ke2? Kc4 2 Ke3 Kc3 3 Ke2 Kc2 4 Ke3 Kd1 5 Kf3 h5! 6 Kf2 Kd2 7 Kg2 Ke2 8 Kh3 Kf3 9 Kh2 Kf2 10 Kh3 Kg1 and White -- in zugzwang -- must commit hari kari by 11 g4.:0; h5:Incorrect. Insufficient is 1 h5? gxh5 2 Kg2 h4! 3 gxh4 Kc3 and Black’s king will prevail on the kingside.:0}]

9.
[{F:W}
{B:8/8/4K1p1/5p1k/6pP/4P1P1/8/8 WHITE}
{QM:Composed by Pospisil. White to play and win; Kf6:Incorrect. This is sticky, because Black is aiming for stalemate after 1 Kf6? f4! 2 exf4 g5 3 fxg5:0; Kf7:Incorrect. After 1 Kf7? f4! leads to stalemate:0; Ke7:Correct. This defense no longer works against 1 Ke7! Kh6 (offers more resistance than 1...g5 2 hxg5 Kxg5 3 Kg7 Kh5 4 Kf6) 2 Kf8! (not 2 Kf7? Kh7 holding the opposition) Kh5 3 Kg8! (again not 3 Kg7? f4!) Kh6 4 Kh8! Kh5 5 Kh7 g5 (or 5...f4 6 exf4 g5 7 f5! gxh4 8 f6 hxg3 9 f7 g2 10 f8/Q g1/Q 11 Qh6 mate) 6 hxg5 f4 7 gxf4 g3 8 g6 g2 9 g7 g1/Q 10 g8/Q and it’s all over after a flurry of checks (10...Qb1+ 11 Kh8 Qa1+ 12 Qg7 Qa8+ 13 Kh7 Qe4+ 14 Kg8! Qa8+ 15 Qf8 Qg2+ 16 Kh8 Qb2+ 17 Qg7 Qb8+ 18 Kh7 Qb1+ 19 Kg8 Qb8+ 20 Qf8 Qb3+ 21 Qf7+ Qxf7 22 Kxf7 with two extra pawns).:10}]

10.
[{F:W}
{B:8/5p2/6k1/3p4/3p1P2/3P1K1P/8/8 WHITE}
{QM:Composed by Rothlander. White to play and win; Kg4:Incorrect. Black is basically a pawn down because his doubled pawns count as one, but White is stymied after 1 Kg4? f5+ 2 Kh4 Kh6.:0; f5+:Correct. White sacrifices to create an outside passed pawn and make space to penetrate with his king by 1 f5+! Kxf5 (if 1...Kg5 2 f6!) 2 h4 Ke5 (or 2...Kg6 3 Kg4 Kh6 4 h5) 3 Kg4 f6 4 h5 Ke6 5 h6 Kf7 6 Kf5 and wins.:10; h4:Incorrect. White can make no further progress after 1 h4? Kh5 2 Kg3 f5.:0}]

11.
[{F:W}
{B:8/5pp1/7p/5P1P/2k3P1/2p5/5P2/2K5 WHITE}
{QM:Edward Lasker-Molle, Berlin 1904. White to play and win; f4:Incorrect. In the actual game, White resigned after 1 f4? f6 3 g5 Kd4.:0; f6:Correct. White missed a win by 1 f6! gxf6 2 f4 Kd4 3 g5! fxg5 5 fxg5 Ke5 6 gxh6 Kf6 7 Kc2 and the h-pawn will queen after Black’s king abandons f6.:10; g5:Incorrect. What a difference one move makes! 1 g5? f6! (of course not 1...hxg5? 2 f6 gxf6 3 h6) stops White cold.:0}]

12.
[{F:W}
{B:8/7p/k1p2p2/4pp2/1PP5/4KPP1/7P/8 WHITE}
{QM:Mason-Englisch, London 1883. White to play and win; g4:Incorrect. After 1 g4? fxg4! (but not 1...f4+ 2 Ke4 h6 3 h4 Kb6 4 g5 fxg5 5 hxg5 hxg5 6 Kxe5 g4 7 Kxf4 gxf3 8 Kxf3 Kc7 9 Ke4 Kd6 10 Kf5) 2 fxg4 h6 3 h4 Kb6 4  Ke4 Kc7 5 g5 fxg5 6 hxg5 hxg5 7 Kxe5 g4 8 Kf4 Kd6 9 Kxg4 Ke5.:0; f4:Incorrect.White’s king has no point of entry after 1 f4? which is met by h5:0; h3:Correct. The subtle 1 h3! h5 (if 1...Kb6 2 g4 fxg4 3 hxg4 followed by Ke4-f5 wins) 2 g4 fxg4 3 fxg4 hxg4 4 h4! wins because this passed pawn can’t be stopped.:10}]

13.
[{F:W}
{B:8/4k3/8/1p2Pp2/p7/P1K1P3/1P6/8 WHITE}
{QM:Alekhine-Yates, Hamburg 1910. White to play and win; Kd3:Correct. After 1 Kd3! Kd7 2 e4! f4 3 Ke2 Ke6 4 Kf2! Kxe5 5 Kf3 Black resigned because he is in zugzwang. Also 1 e4! f4 2 Kd2 Ke6 3 Ke2 Kxe5 4 Kf3 transposes into the winning line.:10; Kd4:Incorrect. A race to queen leads to a draw after 1 Kd4? Ke6 2 Kc5 Kxe5 3 Kxb5 Ke4 4 Kxa4 Kxe3 5 b4 f4 6 b5 f3 7 b6 f2 8 b7 f1/Q 9 b8/Q Qc4+ 10 Qb4 Kd3! 11 Ka5 (if 11 Qxc4+ Kxc4 12 Ka5 Kc5) Qc7+.:0; Kb4:Incorrect. A draw is reached via 1 Kb4? Ke6 2 Kxb5 Kxe5.:0}]

14.
[{F:W}
{B:8/3k2pp/1p3p2/2p2K2/P4P2/8/1P4PP/8 WHITE}
{QM:Thomas-Maroczy, Nice 1930. White to play and win; g4:Incorrect. Black has time to drive out the intruder after 1 g4? Ke7 2 h4 g6+ 3 Ke4 Kd6.:0; h4:Correct. White can maintain his active king on f5 by 1 h4! Ke7 2 h5 Kf7 (if 2...h6 3 Ke4! as in "c") 3 Ke4 Ke6 4 f5+ Kd6 5 Kd3! and Black, in zugzwang, resigned in view of 5...Kd5 (or 5...Ke5 5 Kc4) 6 b3 Kd6 7 Kc4 Kc6 8 g3 h6 9 g4 Kc7 10  Kb5 Kb7 11 a5 bxa5 12 Kxc5 Ka6 13 Kc6.:10; Ke4:Incorrect. Too passive is 1 Ke4? Ke6 and White has made no progress.:0}]

15.
[{F:W}
{B:8/4p3/2p5/2K5/8/8/P4k2/8 WHITE}
{QM:Composed by Grigoriev. White to play and win; a4:Incorrect. White queens first after 1 a4? e5 2 a5 e4 but it’s only a draw.:0; Kxc6:Incorrect. Inadequate is 1 Kxc6? Kf3! 2 Kd5 Kf4! 3 a4 (or 3 Ke6 Ke4 4 a4 Kd4 5 a5 Kc5 6 a6 Kb6 catching the pawn) e5 4 a5 e4 and once again White queens first but can’t win.:0; Kd4:Correct. The paradoxical retreat 1 Kd4! is the only winning move! The most testing defense is 1...e5+ (if 1...Kf3 2 a4! Kf4 3 a5 e5+ 4 Kc3! wins or 1...c5+ 2 Kxc5 Kg3 3 a4 e5 4 a5 e4 5 Kd4 Kf4 6 a6 e3 7 Kd3 Kf3 8 a7 e2 9 a1/Q with check!) 2 Kxe5 Ke3 3 a4 Kd3 4 a5 c5 5 a6 c4 6 a7 c3 7 a8/Q c2 8 Qd5+! Ke2 9 Qa2 Kd3 (a cute finish is 9...Kd1 10 Kd4! c1/Q 11 Kd3! and Black is helpless despite his queen) 10 Qb2! Kd2 11 Kd4 Kd1 12 Kd3 c1/Q 13 Qe2 mate.:10}]

16.
[{F:B}
{B:8/8/2k5/6p1/2Pp2p1/8/3K1PP1/8 BLACK}
{QM:Composed by Labourdonnais. Black to play and draw; Kc5:Incorrect. Black loses the battle for the opposition after 1...Kc5? 2 Kd3 g3 3 f3! (but 3 fxg3? g4 turns the tables) Kd6 4 Kxd4, etc.:0; Kd6:Incorrect. Black loses the battle for the opposition again after 1...Kd6? 2 Kd3  g3 (too late)! 3 fxg3 Kc5 4 g4 (an example of "trebuchet" which means that whoever moves loses).:0; g3:Correct. The way to draw is 1...g3! 2 f3! (again 2 fxg3? Kc5 3 Kd3 g4 wins for Black) Kd6 3 Kc2 Kc6 and both sides are held at bay.:10}]

17.
[{F:B}
{B:8/2p1k2p/2P3p1/6P1/5P2/8/6KP/8 BLACK}
{QM:Shirov-Timman, Wijk aan Zee 1996. Black to play and draw; Kf7:Incorrect. 1...Kf7? allows White to gain a vital tempo by 2 h4. Timman, a pawn down, thinking his position was hopeless anyway, resigned without continuing play!:0; Kd6:Correct. The right defense is 1...Kd6! 2 h4 Kxc6 3 f5 Kd6! (in his mind’s eye Timman probably only saw 3...gxf5? 4 h5 Kd6 5 g6 hxg6 6 h6) 4 f6 Ke6 5 Kf3 Kd6 6 Ke4 Ke6 7 Kd4 Kd6 8 Kc4 Ke6 9 Kc5 Kd7 10 Kd5 Ke8! 11 Kc6 Kd8 12 f7 Ke7 13 Kxc7 Kxf7 14 Kd7 Kf8 15 Ke6 Ke8 16 Kf6 Kf8 holding the opposition:10; Ke6:Incorrect. Black can’t afford to lose a tempo by 1...Ke6? 2 h4! Kd5 (no better is 2...Kf5 5 Kf3) 3 f5! gxf5 4 h5 Ke6 (if 4...Ke5 5 h6 f4 6 g6 hxg6 7 h7 wins) 5 Kf3 Ke5 6 h6 Ke6 7 Kf4 and wins easily.:0}]

18.
[{F:B}
{B:8/8/2p5/5kpp/p1p5/P1P2PP1/7K/8 BLACK}
{QM:Teichmann-Blackburne, Berlin 1897.Black to play and win; h4:Correct. Black’s plan is to swap all the kingside pawns and then penetrate with his king to the queenside, but it’s not easy. Correct is 1...h4! 2 Kh3! Ke5! (The only way to win. If 2...hxg3 3 Kxg3 c5 4 Kg2 Kf4 5 Kf2 g4 5 fxg4 Kxg4 6 Kg2 holding the opposition because Black has used up his reserve tempo with c5) 3 f4+ (if 3 gxh4 gxh4 4 Kxh4 Kf4)  gxf4 4 gxh4 Ke4 5 Kg2 (if 5 h5 f3 6 h6 f4+ Ke3! 7 h7 f2 8 h8/Q f1/Q+ 9 Kg4 Qf4+ 10 Kh3 Kf2! wins) Kd3! 6 Kf3 Kxc3 7 h5 Kb3 8 h6 c3 9 h7 c2 10 h8/Q c1/Q with a winning queen and pawn ending.:10; c5:Incorrect. 1...c5? is wrong, because Black needs this reserve tempo in hand to gain the opposition later.:0; g4:Incorrect. Inadequate is 1...g4? 2 f4 h4 3 gxh4 (but not 3 Kg2 hxg3 4 Kxg3 c5! 5 Kg2 Kxf4) Kxf4 4 Kg2.:0}]

19.
[{F:B}
{B:8/8/pppp1k2/1P3Ppp/P1PPK3/7P/8/8 BLACK}
{QM:Ilyukhin-Novopolsky, USSR 1954. Black to play and win; axb5:Incorrect. Two moves lose, one wins! Not 1...axb5? 2 c5! dxc5 3 dxc5 bxc5 4 a5 c4 5 a6 c3 6 Kd3 and Black can resign.:0; cxb5:Incorrect. Equally wrong is 1...cxb5? 2 a5! bxa5 3 c5 dxc5 4 bxc5 a4 5 c6 a3 (or 5...Ke7 6 f6+ Kxf6 7 c7) 6 c7 a2 7 c8/Q a1/Q 8 Qf8 mate!:0; d5+:Correct. The game was adjudicated a win for Black in view of the surprising 1...d5+! 2 cxd5 (if 2 Ke3 cxb5! 3 c5 bxc5 4 dxc5 Kxf5 5 c6 Ke6 gets back in time) cxd5+ 3 Kxd5 axb5 4 Kc6 (a desperate attempt to avoid 4 axb5 g4 5 hxg4 hxg4 6 Ke4 g3 7 Kf3 Kxf5 8 Kxg3 Ke4) g4! 5 hxg4 h4! 6 d5 h3 7 d6 h2 8 d7 h1/Q queening first with check!:10}]

20.
[{F:B}
{B:3k4/p6p/2KP2p1/8/4pP2/4P3/7P/8 BLACK}
{QM:Tarrasch-Schiffers, Nuremburg 1896. Black to play and draw; h6:Incorrect. Black lost after 1...h6? 2 h4! h5 (forced to stop h5 but now Black no longer has g5 at his disposal) 3 Kd5 Kd7 4 Kxe4 Kxd6 5 Kd4 Kc6 6 e4 and wins.:0; Kc8:Correct. Black can draw with the pawn still on h7. 1...Kc8! 2 h4 Kd8 3 Kd5 Kd7 4 Kxe4 Kxd6 5 Kd4 Ke6 6 e4 Kd6 7 Kc4 Kc6 8 Kb4 Kb6  9 Ka4 Kc5! 10 Ka5 Kd4 11 e5 Kd5 12 Ka6 Ke6 13 Kxa7 h6 14 Kb6 g5! 15 hxg5 hxg5 16 fxg5 Kxe5:10; a5:Incorrect. On 1...a5? 2 Kb5! (2 Kd5? Kd7 transposes into "b") Kd7 3 Kxa5 Kxd6   3 Kb4 Kd5 4 Kb5 h6 5 h4 h5 6. Kb4 Ke6 7 Kc4 Kf5 8 Kd4 Kg4 9 Kxe4 Kxh4 10 Kf3 g5 11 e4 g4+ 12 Kg2 g3 13 e5 wins.:0}]

21.
[{F:B}
{B:7k/7p/8/3pP3/1pp4P/5P2/P7/K7 BLACK}
{QM:Taimanov-Botvinnik, Moscow 1953. Black to play and win; d4:Correct. After 1...d4! 2 e6 Kg7 3 f4 Kf6 4 f5 d3 5 Kb2 h5 White resigned because the pawns are unstoppable after 6 Kc1 b3! 7 a4 c3 (if 7 axb3 cxb3 White is in zugzwang).:10; c3:Incorrect. Premature is 1...c3? 2 Kb1 d4 3 Kc2 Kg7 4 f4 Kf7 5 f5 and things are equal:0; Kg7:Incorrect. Inaccurate is 1...Kg7? 2 a4! bxa3 3 Ka2 d4 4 Kxa3 d3 5 Kb2 Kg6 6 f4 and things are equal.:0}]

22.
[{F:B}
{B:5k2/p1p3p1/8/1p2p3/7P/5PP1/P3KP2/8 BLACK}
{QM:Euwe-Alekhine, 34th match game 1935. Black to play and win; c5:Incorrect. The game continued 1...c5? 2 Ke3! and a draw was agreed because if 2...Ke7 3 f4! exf4+ 4 Kxf4. White dashes his king to the queenside while Black’s king is tethered to the kingside.:0; a5:Correct. By creating an outside passed pawn Black can prevent White from getting rid of his weak doubled pawns. 1...a5! 2 Kd3 (no time for 2 Ke3 b4 3 f4 exf4+ 4 Kxf4 a4! 5 Ke3 b3 6 axb3 a3 and White‘s king is outside the square to stop this pawn) a4 3 Kc3 c5 4 g4 Ke7 5 Kd3 Ke6 6 Kc3 Kd5 7 a3 Ke6 8 Kd3 Kd6 9 Kc3 Kd5 10 Kd3 b4 11 axb4 cxb4 12 Kc2 Kc4 13 Kb2 a3+ 14 Ka2 Kc3 wins.:10; Ke7:Incorrect. The drawback to 1...Ke7? is that White has time for 2 Ke3 Ke6 3 f4! exf4 4 Kxf4 dissolving the weakness before steering his king to the queenside.:0}]

23.
[{F:B}
{B:8/pp5p/8/PP2k3/2P2pp1/3K4/6P1/8 BLACK}
{QM:Muller-Rhode, postal game 1897. Black to play and win; f3:Incorrect. Black lost after 1...f3? 2 gxf3 gxf3 3 c5 Kd5 4 c6 bxc6 5 b6 axb6 6 a6!:0; h5:Incorrect. Black will also lose after 1...h5? 2 c5 Kd5 3 c6! bxc6 4 b6! axb6 5 a6.:0; b6:Correct. An elementary precaution wins by 1...b6! 2 axb6 (or 2 c5 bxa5!) axb6 3 c5 bxc5 4 b6 Kd6 5 b7 Kc7 6 b8/Q+ Kxb8 7 Ke4 Kc7 8 Kxf4 h5:10}]

24.
[{F:B}
{B:8/pp4p1/4k1P1/3p4/2PP4/8/4K2P/8 BLACK}
{QM:Stahlberg-Tartakower, offhand game 1934. Black to play and win; dxc4:Incorrect. Black lost after the careless 1...dxc4? 2 h4 a5 3 h5 a4 4 h6 gxh6 5 d5+ Kf6 6 d6 a3 7 d7 Ke7 8 g7 a2 9 g8/Q a1/Q 10 d8/Q mate.:0; a5:Incorrect. Black also loses after 1...a5? 2 h4 a4 3 cxd5+ Kxd5 4 Kd3 a3 5 Kc3 a2 6 Kb2 Kxd4 7 h5 Ke5 8 h6 Kf6 9 h7!:0; Kf5:Correct. A simple path to victory is 1...Kf5! 2 cxd5 Kxg6 followed by Kf7-e7-d6.:10}]

25.
[{F:B}
{B:8/4k3/1p4p1/1P1K3p/7P/8/8/8 BLACK}
{QM:Krutyansky-Zagorovsky, Moscow 1952. Black to play and win; Kd7:Incorrect. Repeating the position by 1...Kd7 2 Ke5 Ke7 leads nowhere.:0; Kf6:Incorrect. Black wants to play 1...g5 but not immediately because of 2 hxg5 Kf7 3 Ke5 Kg6 4 Kf4. And if 1...Kf6? 2 Kc6 g5 3 hxg5+ (this check is crucial because it gains time when Black recaptures) Kxg5 3 Kxb6 h4 and neither side can win after they both queen.:0; Kf7:Correct. The point behind 1...Kf7! is to play g5 at the proper moment. On 2 Kc6 (or 2 Ke5 Kg7 3 Ke4 Kf6 4 Kf4 g5+! 5 hxg5+ Kg6 and White lands in zugzwang) g5 3 Kxb6 (if 3 hxg5 h4 queens too fast) gxh4 4 Kc5 (any other square permits a decisive queen swap, as in 4 Kc7 h3 5 b6 h2 6 b7 h1/Q 7 b8/Q Qh2+ and Qxb8) Ke7! 5 b6 Kd7 stopping the pawn, whereas White cannot do the same.:10}]

26.
[{F:B}
{B:8/p1k5/8/4K2p/P7/8/5P2/8 BLACK}
{QM:Chekhover-Bondarevsky, Leningrad 1938. Black to play and draw; a5:Incorrect. Black lost after 1...a5? 2 Kf5 Kd6 3 Kg5 Ke5 4 f3! Ke6 5 f4 h4 6 Kxh4 Kf6 7 Kg4 Kg6 8 Kf3 Kf6 9 Ke4 Ke6 10 Kd4!:0; Kc6:Correct. Black can draw by 1...Kc6! 2 Kf5 (or 2 a5 h4 3 Kf4 Kd5 7 Kg4 Ke4! 8 Kxh4 Kf3) Kd5 3 Kg5 Ke4! 4 f4 h4.:10; a6:Incorrect. Too slow is 1...a6? 2 Kf5 Kd6 (or 2...h4 3 Kf4 Kd6 4 Kg4 Ke5 5 a5) 3 Kg5 Ke5 4 f4+! Ke6 5 a5.:0}]

27.
[{F:B}
{B:8/8/p1k3p1/2p4p/P1K4P/1P3P2/8/8 BLACK}
{QM:Grob-Nimzovich, Zurich 1934. Black to play and draw; Kb6:Incorrect. Shun 1...Kb6? which White follows by 2 Kd5 and Black is hard-pressed to find a good move.:0; Kd6:Incorrect. Black ends up a pawn down in a difficult queen ending after 1...Kd6 2 f4 Kc6 3 b4! cxb4 4 Kxb4 Kb6 5 a5+ Kc6 6 Kc4 Kd6 7 Kd4 Ke6 8 Kc5 Kf5 9 Kb6 Kxf4 10 Kxa6 g5 11 hxg5 h4 12 g6 h3 13 g7 h2 14 g8/Q h1/Q 15 Qc4.:0; Kd7:Correct. Black drew by 1...Kd7! 2 f4 (more prudent than 2 Kd5? g5! 3 hxg5 h4 4 g6 Ke7 and Black wins! but 2 Kxc5 g5 3 Kd4! draws) Kd6 3 Kd3 a5 4 Kc4 Kc6.:10}]

28.
[{F:B}
{B:8/7p/p4p2/k1pP1Pp1/6P1/P1K5/8/8 BLACK}
{QM:Randviir-Keres, Parnu 1947. Black to play and win; h6:Incorrect. As we have seen, it’s foolish to use up a reserve tempo if it can come in handy later to wrest the opposition. After 1...h6? 2 Kd3 Kb5 3 a4+ Kb6 (the king lands out of the square on 3...Kxa4? 4 d6) 4 Kc4 a5 5 Kd3 Kc7 6 Kc3 Kd7.:0; Kb5:Correct. Black is a pawn up and won with 1...Kb5! (threatening c4) 2 a4+ Kb6 3 Kc4 a5 4 d6 (also hopeless is 4 Kc3 Kc7 5 Kd3 Kd6 6 Kc4 h6! when the reserve tempo decides) Kc6 5 d7 Kxd7 6 Kxc5 Ke7 7 Kd5 (the king must rush to the kingside since 7 Kb5 h5! wins) Kf7 8 Ke4 Kf8! 9 Ke3 Ke7! 10 Ke4 Kd6 11 Kd4 h6 12 Ke4 Kc5 13 Ke3 Kd5 14 Kd3 Ke5 15 Ke3 h5 (finally!) 16 gxh5 Kxf5 17 Kf3 Ke6 18 Kg4 Kf7 19 Kf5 Kg7.:10; Kb6:Incorrect. A draw ensues on 1...Kb6? 2 Kc4 a5 3 a4 h6 (Black uses up his precious tempo to force a retreat) 4 Kc3 Kc7 5 Kd3 Kd7.:0}]

29.
[{F:B}
{B:8/p7/1p4kp/3p4/P2P2K1/8/1P4P1/8 BLACK}
{QM:Euwe-Pirc, 6th match game 1949. Black to play and draw; a5:Incorrect. Black lost after 1...a5? 2 g3 h5+ 3 Kh4 Kh6 4 g4 hxg4 5 Kxg4 Kg6 6 Kf4 Kf6 7 b3! (finally using the reserve tempo decisively) Ke6 8 Kg5 penetrating.:0; a6:Correct. Black has a surprising draw by 1...a6! 2 b4 b5 3 a5 Kf6 4 Kh5 Kf5! (clearly hopeless is 4...Kg7? 5 g4 Kh7 6 g5) 5 Kxh6 Kf4 6 g3+ Kf3! (not 6...Kxg3? Kg5) 7 Kh5 Ke4! 8 g4 Kxd4 9 g5 Kc3 10 g6 d4 11 g7 d3 12 g8/Q d2 and White can’t win because c4 is inacessible to his queen!:10; Kf6:Incorrect. Feeble resistance is offered by 1...Kf6? 2 Kh5 Kg7 3 g4 Kh7 4 g5 hxg5 5 Kxg5 Kg7 6 Kf5 Kf7 7 Ke5 followed by Kxd5.:0}]

30.
[{F:B}
{B:8/6p1/p7/1p6/1P2KP2/P7/6k1/8 BLACK}
{QM:Havasi-Stahlberg, Budapest 1934. Black to play and win; Kf2:Incorrect. Black let the win slip away by 1...Kf2? 2 f5! Kg2 (if 2...Kg3 3 Ke3! Kg4 4 Ke4 keeps the opposition) 3 Kf4 Kf2 (but not 3...Kh3? 4 Kg5 Kg3 9 f6!) 4 Ke4 Kg2.:0; Kg3:Correct. Correct is 1...Kg3! 2 Ke3 g6 3 Ke4 Kf2 4 f5 gxf5+ 5 Kxf5 Ke3 and Black gets to the queenside "fustest with the mostest.":10; g6:Incorrect. Hideous is 1...g6?? 2 f5! gxf5+ 3 Kxf5 Kf3 4 Ke5 and White wins.:0}]

31.
[{F:B}
{B:8/6p1/6Pp/2p4P/2k5/2P5/1K6/8 BLACK}
{QM:Composed by Bahr. Black to play and draw; Kb5:Correct. The only drawing move is 1...Kb5! 2 Kb3 c4!+ 3 Kc2 Kc5 4 Kd2 Kd5 5 Ke3 Ke5 when neither king can penetrate.:10; Kd5:Incorrect. Fatal is 1...Kd5? 2 Kb3 Kd6 3 Ka4 Kc6 4 Ka5 Kd5 5 Kb5 Kd6 6 c4.:0; Kd3:Incorrect. Equally lugubrious is 1...Kd3? 2 Kb3 Ke4 3 Kc4 Kf5 4 Kxc5  Kg5 5 Kd6 Kxh5 6 c4 Kxg6 7 c5 and the pawn queens too fast.:0}]

32.
[{F:B}
{B:8/8/2K1kp2/5p1p/7P/4P1P1/8/8 BLACK}
{QM:Composed by Grigoriev. Black to play and draw; Ke5:Incorrect. The natural 1...Ke5? loses to 2 Kd7 Ke4 3 Ke6 Kxe3 (or 3...Kf3 4 Kxf6! Kxg3 5 Kxf5 Kxh4 6 Kf4! Kh3 7 e4) 4 Kxf5! Kf3 5 Kxf6 Kxg3 6 Kg5.:0; Ke7:Incorrect. 1...Ke7? 2 Kc7 Ke6 3 Kd8 Ke5 4 Ke7 leads to the same fate.:0; f4:Correct. A process of elimination shows that Black’s only hope is 1...f4! 2 gxf4 Kf5 3 Kd5 Kg4 4 Ke6 Kxh4 5 Kxf6 Kg4 6 e4 h4.:0}]

33.
[{F:W}
{B:8/2k1p2p/3p4/6P1/8/5K2/3P4/8 WHITE}
{QM:Composed by Zhigis. White to play and draw; Kg4:Correct. A pawn down on an open board, it is hard to believe that stalemate is White’s saving resource. 1 Kg4 Kd7 2 Kf5! (not 2 Kh5? Ke6 3 Kh6 Kf5) Ke8 (if 2...d5 3 Ke5 e6 4 Kf6) 3 Ke6 Kf8 4 d3! Ke8 5 d4 Kd8 6 d5 Ke8 7 g6! hxg6.:10; Kf4:Incorrect. White can’t afford to lose a tempo by 1 Kf4? Kc6 2 Kf5 Kd5 with an active king instead of being forced back to the first rank (as in "a").:0; Ke4:Incorrect. Again, White can’t afford to lose a tempo by Ke4? Kc6 2 Kf5 Kd5.:0}]

34.
[{F:W}
{B:8/6p1/5k2/8/3K4/8/1P6/8 WHITE}
{QM:Composed by Duras. White to play and win; Kc5:Correct. 1 Kc5! Kg6 (no better is 1...g5 2 b4 g4 3 Kd4! Kg5 4 b6 g3 5 Ke3 Kg4 6 b6 Kh3 7 b7 g2 8 Kf2 Kh2 9 b8/Q+) 2 b4 Kf7 3 b5 Ke7 4 Kc6! Kd8 5 Kb7!! g5 6 b6 g4 7 Ka8 g3 8 b7 g2 9 b8/Q and White queens first with check!:10; Kc3:Incorrect. The tame 1 Kc3? Kg6 2 b4 Kf7 3 b5 Ke7 enables Black to stop the pawn.:0; Kc4:Incorrect. A draw also ensues after 1 Kc4? Kg6.:0}]

35.
[{F:W}
{B:8/8/8/k6p/2P1K1pP/8/8/8 WHITE}
{QM:Evans-McCormick, Lone Pine 1971. White to play and draw; Kd5:Incorrect. White’s king is chained to the protected passed pawn on g4 which is three squares away from queening. He cannot get back in time to stop it after 1 Kd5? g3. In such situations the king must stay "within the square.":0; c5:Incorrect. White lost after 1 c5? Ka6 2 Kd4 Kb7 3 Ke4 Kc6 4 Kd4 Kb5! 5 Kd5 g3 6 c6 Kb6! 7 Kd6 g2 8 c7 g1/Q 9 c8/Q Qd4+ 10 Ke7 Qxh4+ 11 Kf8 Qf4+ 12 Ke8 Qe5+ 13 Kf7 Qc7+ 14 Qxc7+ Kxc7.:0; Kd3:Correct. White must stand pat whilst keeping an eye on the g-pawn. The drawing resource is 1 Kd3! Ka4 2 Ke4 Kb4 3 Kd4! (but not 3 Kd3? Kc5 4 Kc3 g3) and Black can’t make headway.:10}]

36.
[{F:W}
{B:8/8/8/pp2pk1p/2p5/2P1KPP1/PP6/8 WHITE}
{QM:Evans-Benko, Las Vegas 1966. White to play and win; a3:Incorrect. The game was drawn after 1 a3? Kf6! 2 Ke4 Ke6 3 Ke3 Kf6. White intended 4 g4 (but it must be played with check or Black is not forced to capture) and saw too late that it loses to 4...h4! 5 Kf2 Kg5 6 Kg2 e4 7 fxe4 Kxg4.:0; g4+:Correct. White will never get another chance for 1 g4 with check, which forces Black to capture by 1...hxg4 2 fxg4+ Kxg4 3 Ke4 and the rest is a matter of simple arithmetic (3...Kg3 4 Kxe5 Kf3 5 Kd5 Ke3 6 Kc5 Kd3 7 Kxb5 Kc2 8 Kxc4 Kxb2 9 a4 Ka3 10 Kb5 Kxc3 11 Kxa5 and the pawn will queen.:10; Kf2:Incorrect. 1 Kf2? e4 2 Ke3 exf3 3 Kxf3 leads to a Mexican standoff.:0}]

37.
[{F:W}
{B:5K2/1p5p/3k3P/P7/4p3/8/5P2/8 WHITE}
{QM:Composed by Grigoriev. White to play and win; Kf7:Incorrect. On 1 Kf7? Kd7 2 Kf6 Kd6 holds the opposition (for 3 Kg7 see "b").:0; Kg7:Incorrect. White can’t extricate his king from the corner after 1 Kg7? Ke7 2 Kxh7 Kf7 3 Kh8 Kf8.:0; Ke8:Correct. A finesse is required to shatter Black’s resistance. 1 Ke8! Ke6 (if 1...Kc6 2 Ke7! Kc5 3 Ke6 or 1...Ke5 2 Kd7! Kf4 3 Kd6! Kf3 4 Ke5) 2 Kd8 Kd6 3 Kc8 Kc6 4 Kb8 Kb5 5 Kxb7 Kxa5 6 Kc6 Ka6 7 Kd5 Kb6 8 Kxe4, etc.:10}]

38.
[{F:W}
{B:8/8/8/6pp/Kpk5/6PP/P7/8 WHITE}
{QM:Composed by Grigoriev. White to play and draw; g4:Correct. Curiously, all moves except 1 g4! lose for White. On 1...h4! (not 1...hxg4? 2 hxg4 Kc5 3 Ka5 Kc4 4 Kb6 wins) 2 Ka5 Kc5! 3 Ka4 Kc4 repeats moves.:10; h4:Incorrect. Black queens too fast after 1 h4? g4! 2 Ka5 b3 3 axb3+ Kxb3 4 Kb5 Kc3 5 Kd5 Kd3 6 Ke5 Ke3 7 Kf5 Kf3 (as in "c").:0; Ka5:Incorrect. Hopeless is 1 Ka5? g4! 2 hxg4 hxg4 3 Ka4 Kc3 4 Kb5 b3 5 axb3 Kxb3 6 Kc5 Kc3 7 Kd5 Kd3 8 Ke5 Ke3 9 Kf5 Kf3 gobbling the pawn on g3 next.:0}]

39.
[{F:W}
{B:8/8/8/3k3p/7P/7K/4P3/8 WHITE}
{QM:Composed by Grigoriev. White to play and win; Kg3:Correct. The tricky solution is 1 Kg3! Ke4 2 Kg2! Ke3 (another pretty variation is 2...Kf4 3 Kf2 Kg4 4 Ke3! Kxh4 5 Kf4 Kh3 6 e4 h4 7 e5 Kg2 8 e6 h3 9 e7 h2 10 e8/Q h1Q 11 Qe2+ Kg1 12 Kg3! and White is helpless despite his queen) 3 Kf1 Ke4 4 Ke1 Ke3 5 Kd1 Kf4 6 Kd2 Ke4 (again if 6...Kg4 7 Ke3 Kxh4 8 Kf4 wins) 7 e3 Kf3 8 Kd3 Kg3 9 Ke4! (not 9 e4? Kxh4) Kg4 10 Ke5 Kxh4 11 Kf4 Kh3 12 e4 Kg2 13 e5! h4 14 e6 winning as shown above.:10; Kg2:Incorrect. If 1 Kg2 Ke4 2 Kf2 Kf4! draws. If it were Black's move, White could win here!:0; Kh2:Incorrect. Black holds against 1 Kh2 Kd4! 2 Kg2 Ke4! 3 Kf2 Kf4= and again White finds himself on the move and thus can make no progress (4 Kf1 Kg4).:0}]

40.
[{F:W}
{B:7k/6p1/8/4pP1p/8/6P1/7K/8 WHITE}
{QM:Composed by Halberstadt. White to play and draw; Kg2:Incorrect. White perishes after 1 Kg2? Kh7 2 Kf3 Kh6 3 Ke4 Kg5 4 Kxe5 Kg4 5 Ke6 Kxg3 6 Kf7 Kg4.:0; g4:Correct. A pawn down, White must fight for a draw by 1 g4! hxg4 (or 1...Kh7 2 g5! g6 3 f6 Kg8 4 Kg3 Kf7 5 Kf3 Ke6 6 Kg3) 2 Kg3 Kh7 3 Kh4! (not 3 Kxg4? Kh6 4 Kh4 e4 5 Kg3 e3) Kh8 4 Kxg4 Kg8 5 Kh4! Kf7 6 Kg5 and Black can’t utilize his extra pawn.:10; Kh3:Incorrect. Inadequate is 1 Kh3? e4! 2 Kg2 Kh7 3 Kf2 Kh6 4 Ke3 Kg5 5 Kxe4 Kg4 transposing into "a.":0}]

41.
[{F:W}
{B:8/1pp5/1p4p1/3Pp1k1/PP2P2p/5K2/5P1P/8 WHITE}
{QM:Wade-Korchnoi, Buenos Aires 1960. White to play and win; b5:Correct. White created a deadly passed pawn with 1 b5! Kh5 (no better is 1...Kf6 2 Kg4 g5 3 Kh5) 2 a5! bxa5 3 b6! cxd6 4 d6 and this foot soldier marches to glory.:10; h3:Incorrect. White also wins but it takes longer after 1 h3 b5! 2 axb5 b6 3 Ke3 Kf6 4 f4 g5 5 f5 Kf7 6 Kf3 Kg7 7 Kg4 Kh6 8 f6 Kg6 9 f7 Kxf7 10 Kxg5, etc.:0; a5:Incorrect. Black wrests the advantage after 1 a5? bxa5 2 bxa5 Kh5 3. h3 g5.:0}]

42.
[{F:W}
{B:6K1/3k2P1/8/8/8/8/7r/4R3 WHITE}
{QM:The Lucena Position. White to play and win; Kf7:Incorrect. White merely goes around in circles after 1 Kf7 Rf2+ 2 Kg6 Rg2+ 3 Kh7 Rh2+ 4 Kg8 Rg2.:0; Re4:Correct. The Lucena position, discovered over 500 years ago, is akin to the Rosetta stone of chess. This type of ending with the pawn on its seventh rank has occurred countless times. The key to victory is shielding the king from incessant checks by "building a bridge" with 1 Re4! Rh1 2 Kf7 Rf1+ 3 Kg6 Rg1+ 4 Kf6 Rf1+ 5 Kg5 Rg1+ 6 Rg4! Rxg4+ 7 Kxg4 and the pawn queens.:10; Re5:Incorrect. Less accurate is 1 Re5 Kd6 2 Kf7? (2 Re4! gets back to a simpler win) Rf2+ 3 Ke8 Kxe5 4 g8/Q leading to a long queen vs. rook ending that Rf2+ requires technical expertise to win.:0}]

43.
[{F:W}
{B:8/R7/8/8/4pk2/8/7r/4K3 WHITE}
{QM:The Philidor Position. White to play and draw; Ra3:Correct. In the late 18th century Andre Philidor showed that the easiest way to draw this basic ending is to keep White‘s rook on the third rank to prevent the king from penetrating and then going to the eighth rank after the pawn pushes. Thus 1 Ra3! e3 (or 1...Rb2 2 Rc3 waiting) 2 Ra8! and Black can make no progress.:10; Rf7+:Incorrect. White can still draw after 1 Rf7+ Ke3 2 Kf1 but makes it hard for himself.:0; Kf1:Incorrect. Again, White makes his task unnecessarily difficult with 1 Kf1 Kf3 2 Rf7+ Ke3.:0}]

44.
[{F:W}
{B:5R2/8/8/8/4p3/4k3/7r/4K3 WHITE}
{QM:Analysis by Philidor. White to play and draw; Rf1:Incorrect. It’s easy to dispose of 1 Rf1? with Ra2 followed by Ra1+.:0; Kd1:Incorrect. Also bad is 1 Kd1? Rh1+ 2 Kc2 Ke2 ushering the pawn home.:0; Kf1:Correct. The best defense is going to the short side by 1 Kf1! Rh1+ 2 Kg2 Re1 3 Ra8! Rd1 4 Re8! Kd2 5 Kf2 preventing White from freeing his king by Ke2.:10}]

45.
[{F:W}
{B:3R4/4K3/r2P4/4k3/8/8/8/8 WHITE}
{QM:Composed by Kling-Horwitz. White to play and win; d7:Incorrect. A tasty trap is 1 d7? Re6+ 2 Kf7 Rf6+! (but not 2...Kd6? 3  Re8!) 3 Kg7 Ke6 4 Re8+ Kxd7 5 Kxf6 Kxe8 and it’s down to bare knuckles.:0; Rh8:Correct. In general, a rook should stay as far away as possible when planning checks on an open board. A simple win is 1 Rh8! Rxd6 2 Rh5+ Kf4 Kxd6.:10; Rg8:Incorrect. White throws away the win by 1 Rg8? Rxd6 2 Rg5+ Kf4 3 Kxd6 Kxg5.:0}]

46.
[{F:W}
{B:8/2P5/1K1r4/8/8/8/8/k7 WHITE}
{QM:Potter-Fenton, England 1895. White to play and win; Kc5:Incorrect. It’s a draw after 1 Kc5? Rd1 2 Kc6 (the rash 2 c8/Q? Rc1+ and Rxc8 wins for Black!) Rc1+ 3 Kb7.:0; Kb5:Correct. This is considered the most famous of all chess studies and is sometimes called the Saavedra position because a monk by that name first discovered the underpromotion of the pawn to a rook at move 5. The actual game was drawn but White missed a splendid win by 1 Kb5! Rd5+ 2 Kb4 Rd4+ 3 Kb3 Rd3+ 4 Kc2 Rd5! (hoping for 5 c8/Q? Rc5+ 6 Qxc5 stalemate) 5 c8/R! Ra5 (necessary to stop 6 Ra8) 6 Kb3! and White either mates or captures the rook.:10; Kb7:Incorrect. If 1 Kb7? Rd7 draws by pinning the pawn and then giving up the rook to stop it from queening.:0}]

47.
[{F:W}
{B:6k1/4K3/8/r4p2/4P3/8/8/5R2 WHITE}
{QM:Composed by Selesniev. White to play and win; exf5:Incorrect. The insipid 1 exf5? Ra7+ 2 Kf6 Ra6+ 3 Kg5 Kf7 reaches the Philidor position.:0; Rg1+:Correct. An incredible pawn sacrifice lures Black’s rook to a fatal square. 1 Rg1+ Kh7 2 e5! (not a typo!) Rxe5+ (or 2...f4 3 e6 f3 4 Kf6! f2 5 Rf1 Kg8 6 Rxf2 Kf8 7 Rb2 Ra8 8 Rh2 Kg8 9 Rg2+ Kf8 10 e7+ also wins) 3 Kf7 Kh6 4 Kf6 threatening Rh1 mate and/or Kxe5. Chessboard magic!:10; Rxf5:Incorrect. Insufficient is 1 Rxf5? Ra7+ 2 Kd6 Ra6+ 3 Ke5 Ra5+ 4 Kf4 Rxf5+ 5 Kxf5 Kf7 6 Ke5 Ke7. Black has the opposition.:0}]

48.
[{F:W}
{B:8/3r4/2k5/2p5/8/4K3/8/2R5 WHITE}
{QM:Kochiev-Smyslov, Lvov 1978. White to play and draw; Ke4:Correct. White wants to cross over to the queenside with his king to blockade the pawn. But it can’t be done, so his best defense is to shuffle from e4 to e3 while trying to restrain the forward march of the pawn. Thus 1 Ke4! Rd4+ 2 Ke3 Kb5 3 Rb1+ Kc4 (if 3...Rb4 4 Rc1 c4 5 Kd4) 4 Rc1+ Kb4 5 Rb1+ Ka4 6 Rc1! Rd5 7 Ke4! Rh5 8 Kd3!:10; Ke2:Incorrect. White lost after 1 Ke2? Kb5 2 Rb1+ Ka4 3 Rc1 Kb4 4 Rb1+ Ka3 5 Rc1 Rd5! and now Ke4 is no longer possible because the king is on e2.:0; Rc2:Incorrect. There’s no single rule to govern these positions because the outcome often depends on one tempo. Nonetheless, an important principle is to keep the rook far away from the enemy king when checking. Violating this principle is 1 Rc2? Kb5 2 Rb2+ (or 2 Rd2 Rxd2 3 Kxd2 Kb4! 4 Kc2 Kc4 seizing the opposition wins) Kc4 3 Rc2+ Kb4 4 Rb2+ Kc3 followed by c4 wins for Black.:0}]

49.
[{F:W}
{B:4K3/4P3/8/8/7k/R7/p7/r7 WHITE}
{QM:Composed by Keres. White to play and win; Kf7:Incorrect. Black checks to his heart’s content after 1 Kf7? Rf1+ 2 Kg7 (if 2 Ke8 Rf2!) Rg1+ and so on.:0; Kd7:Incorrect. Going the other way also provides no shelter after 1 Kd7 Rd1+ 2 Kc7 Rc1+.:0; Ra5:Correct. Black gets in zugzwang after 1 Ra5! Kg4 (or 1...Kh3 2 Ra4!) 2 Kf7! Rf1+ 3 Kg6 Re1 (3...a1/Q 4 Rxa1 Rxa1 5 e8/Q leads to a theoretical queen vs. rook win) 4 Ra4+ Kh3 5 Kf6 Rf1+ 6 Kg5 Rg1+ 7 Kh5 Re1 8 Ra3+! Kg2 9 Rxa3+ Kf3 10 Ra7 Re6! (the toughest defense) 11 Kg5 Ke4 12 Rb7! (but not the obvious 12 Rd7? Ke5! when White is in zugzwang) Ke5 13 Rd7! Ke4 14 Rd1! Kf3 (14...Rxe7 15 Re1+ and Rxe7 costs the rook) 15 Rf1+ Ke2 16 Rf7 Ke3 17 Kf5 wins. Whew!:10}]

50.
[{F:W}
{B:2K5/2P4R/8/k7/8/8/2r4p/8 WHITE}
{QM:Composed by Em. Lasker. White to play and win; Rh5+:Incorrect. Black’s king is driven to a better position after 1 Rh5+ Kb6 2 Rh6+ Ka7.:0; Kb7:Correct. A curious stepping maneuver leads to a queen vs. rook finale with 1 Kb7! Rb2+ 2 Ka7 Rc2 3 Rh5+ Ka4 (the king is forced back) 4 Kb7 Rb2+ 5 Ka6 Rc2 6 Rh4+ Ka3 7 Kb6 Rb2+ (White was threatening Rxh2) 8 Ka5! Rc2 9 Rh3+ Ka2 10 Rxh2! Rxh2 11 c8/Q.:10; Kd8:Incorrect. A loss of time is 1 Kd8 Rd2+ 2 Ke8 Re2+ but White can still find the winning idea with 3 Kd7 Rd2+ 4 Kc6 Rc2+ 5 Kb7 Rb2+ 6 Ka7 Rc2 7 Rh5+:0.}]
