The Five Basic Themes Tutorial



1.
[{B:4k1r1/p2n1p1R/1pr5/5P2/8/P7/5PB1/3R2K1}{QB:1. How should White unpin the bishop?{W:9_01}{A:Wg1f1}{H1:f1}{W:9_01a}{H1:d1h7}{W:9_01b};1. Kg1-f1;
{B:4k1r1/p2n1p1R/1pr5/5P2/8/P7/5PB1/3R2K1}{S:g1f1}{W:9_01I}Incorrect. Moving away (1. Kg1-f1) gets the White king off the g-file, ending the pin of the g8-rook on the bishop. With the bishop no longer pinned, it can shift into gear and take Black's rook at {A:Wg2c6}{N1:c6}{W:9_01Ia}c6. But Black has a free move. He can extricate the rook quite easily, and so White isn't able to win anything. Breaking the pin in this way, by taking the time to move the king, is simply too slow to succeed.;
1. Move a rook;{B:4k1r1/p2n1p1R/1pr5/5P2/8/P7/5PB1/3R2K1}{N1:d1h7}{W:9_01C}Correct. It's a rook move that does the trick, and an absurd-looking one at that, {C}{S:h7h8}{W:9_01Ca}1. Rh7-h8!. White puts an end to the g-file pin by diverting Black's rook off the g-file, sacrificing his own rook in the corner. Note that a pinned piece can't move for actual or practical reasons, in that it shields another piece (or important square) behind it along the line of attack. After White's rook moves to h8, Black essentially has two choices, both of which fail. He can take White's rook, or he can protect his rook at g8. If he takes White's rook {S:g8h8}{W:9_01Cb}(1... Rg8xh8), the pin on the g-file has ceased to be and the bishop can then take the c6-rook for nothing {S:g2c6}{W:9_01Cc}(2. Bg2xc6). This capture happens to turn the pinning concept around, for it suddenly puts the knight in a pin. The knight can't move because it shields Black's king from the bishop's attack. Since the knight is attacked twice (by White's rook{A:Wd1d7}{A:Wc6d7}{W:9_01Cd} and bishop), and since Black can't add a second protector to the knight (only the king can defend it), the steed is lost. Instead of taking the rook {B:4k1rR/p2n1p2/1pr5/5P2/8/P7/5PB1/3R2K1}{A:Bg8h8}{N1:h8}{W:9_01Ce}(1... Rg8xh8), Black might try to guard his own rook, say {R}{C}{S:d7f6}{W:9_01Cf}1... Nd7-f6. But this doesn't help, for White just trades rooks on g8 {S:h8g8}{W:9_01Cg}(2. Rh8xg8+ {S:f6g8}{W:9_01Ch}Nf6xg8), terminating the pin quite effectively, by destroying the pinner. With the pin gone, the bishop is then capable of removing the rook on c6 {S:g2c6}{W:9_01Ci}(3. Bg2xc6+) for free. White comes away with a decisive material gain in either case.}]

2.
[{B:4k1rR/p2n1p2/1p4r1/5P2/8/P7/5PB1/3R2K1}{QB: 2. Which rook should White take?{W:9_02}{A:Wf5g6}{H1:g6}{W:9_02a}{A:Wh8g8}{H1:g8}{W:9_02b};The rook at g6;
{B:4k1rR/p2n1p2/1p4r1/5P2/8/P7/5PB1/3R2K1}{S:f5g6}{W:9_02C}Correct. Taking the rook at g6 (1. f5xg6) is the winning capture. There's a roadblock, however, for Black initially keeps the game even by taking White's rook {S:g8h8}{W:9_02Ca}(1... Rg8xh8). But with one pin over and done with (Black's original pin on the g-file), White can create a pin of his own. He can move the bishop to c6 {S:g2c6}{W:9_02Cb}(2. Bg2-c6), and Black's {N1:d7}{W:9_02Cc}d7-knight is indefensible. White thereby gains a piece.;
The rook at g8;{B:4k1rR/p2n1p2/1p4r1/5P2/8/P7/5PB1/3R2K1}{S:h8g8}{W:9_02I}Incorrect. Exchanging rooks on g8 (1. Rh8xg8+ {S:g6g8}{W:9_02Ia}Rg6xg8) adds nothing, for White's bishop{N1:g2}{W:9_02Ib} is still pinned along the g-file and can't move. However White continues, whether he ends the pin, or checks Black's king, or whatever, Black will have little trouble avoiding the possibility of a pin along the {N1:a4b5c6d7e8}{W:9_02Ic}a4-e8 diagonal. For example, he can simply move his king up {A:Be8e7}{W:9_02Id}to e7.}]

3.
[{F:B}{B:2rqkb1r/1p1bpp2/3p2p1/pB4B1/1n2P1n1/1NN4P/PPP1Q1P1/R3K2R}{QB:3. Which knight should Black move?{W:9_03}{H1:g4}{W:9_03a}{H1:b4}{W:9_03b};The one on g4;
{F:B}{B:2rqkb1r/1p1bpp2/3p2p1/pB4B1/1n2P1n1/1NN4P/PPP1Q1P1/R3K2R}{N1:g4}{W:9_03I}Incorrect. Black, as an illustration, can save his g4-knight by moving it to e5 {C}{A:Bg4e5}{W:9_03Ia}(1... Ng4-e5), though the pin on the {N1:h3}{W:9_03Ib}h3-pawn (Black's h8-rook to White's h1-rook) dissuades White from taking the knight anyway (if {R}{C}{S:h3g4}{W:9_03Ic}2. h3xg4, then {S:h8h1}{W:9_03Id}2... Rh8xh1+). After the repositioning, {B:2rqkb1r/1p1bpp2/3p2p1/pB4B1/1n2P1n1/1NN4P/PPP1Q1P1/R3K2R}{S:g4e5}{W:9_03Ie}1... Ng4-e5, Black has a fine game but the material is even. And since from the original position he has a way to gain, this can't be the right way to go.;
The one on b4;{B:2rqkb1r/1p1bpp2/3p2p1/pB4B1/1n2P1n1/1NN4P/PPP1Q1P1/R3K2R}{N1:b4}{W:9_03C}Correct. It's Black's queen-knight that can do the damage, by brashly capturing on c2 with check {C}{S:b4c2}{W:9_03Ca}(1... Nb4xc2+). This also forks the rook at {N1:a1}{W:9_03Cb}a1, so White has nothing better than taking the knight with his queen {C}{S:e2c2}{W:9_03Cc}(2. Qe2xc2). But recapturing on c2 reduces the number of defenders on b5 by one, and it also puts the {N1:c3}{W:9_03Cd}c3-knight in a pin. The knight can't move productively because it's shielding White's queen from capture by the {N1:c8}{W:9_03Ce}c8-rook. So Black takes the b5-bishop {C}{S:d7b5}{W:9_03Cf}(2... Bd7xb5), and White's {S:c3b5}{W:9_03Cg}c3-knight can't safely take back. Note that in the end Black's {N1:g4}{W:9_03Ch}g4-knight still can't be taken because {N1:h3}{W:9_03Ci}the h3-pawn remains pinned. Black has won a pawn.}]

4.
[{F:B}{B:r4rk1/pp2bpp1/7p/8/2BBP3/8/P5P1/qN1Q2K1}{QB:4. How should Black save his queen?{W:9_04}{A:Be7c5}{H1:c5}{W:9_04a}{A:Ba8d8}{H1:d8}{W:9_04b};a bishop pin;
{F:B}{B:r4rk1/pp2bpp1/7p/8/2BBP3/8/P5P1/qN1Q2K1}{W:9_04I}Incorrect. The diagonal pin, {S:e7c5}{W:9_04Ia}1... Be7-c5, is messy. True, it saves the queen by pinning the d4-bishop to White's king along the {N1:a7b6c5d4e3f2g1}{W:9_04Ib}a7-g1 diagonal. But it's costly, for after White takes the c5-bishop {C}{S:d4c5}{W:9_04Ic}(2. Bd4xc5), he has an assemblage of three minor pieces against Black's two rooks, which is approximate material equality. Obviously, the creation of this material imbalance makes the assessment of the position problematic. Sometimes two rooks are better than three minor pieces, sometimes the three minor pieces out-maneuver the rooks. Why go into a nebulous situation when Black has clearer and better?;
a rook pin;{F:B}{B:r4rk1/pp2bpp1/7p/8/2BBP3/8/P5P1/qN1Q2K1}{W:9_04C}Correct. The pin {S:a8d8}{W:9_04Ca}(1... Ra8-d8) gets ready to answer the capture of Black's queen {S:d4a1}{W:9_04Cb}(2. Bd4xa1) with the counter-capture of White's {S:d8d1}{W:9_04Cc}(2... Rd8xd1+). After this proposed trade of queens, Black is cleaning up. So White has to try to close the d-file with {F:B}{B:3r1rk1/pp2bpp1/7p/8/2BBP3/8/P5P1/qN1Q2K1}{S:c4d5}{W:9_04Cd}2. Bc4-d5, and this obstruction renews the threat to Black's queen. But Black clears the air with the annihilating {S:d8d5}{W:9_04Ce}2... Rd8xd5!, giving up the exchange (a rook for a minor piece) to get control of the position. White can take back {S:e4d5}{W:9_04Cf}(3. e4xd5), but now with a2 no longer protected by the non-existent light-square bishop, Black's queen can escape at a2 {S:a1a2}{W:9_04Cg}(3... Qa1xa2). The resulting position has Black ahead by the exchange and three pawns, which is usually a winning advantage wherever chess is played.}]

5.
[{F:B}{B:r2qkb1r/pp1bpppp/2np4/1N4B1/4PPn1/2N5/PPP3PP/R2QKB1R}
{QB:5. Should Black chase the b5-knight or threaten mate?{W:9_05}{A:Ba7a6}{H1:a6}{W:9_05a}{A:Bd8b6}{H1:b6}{W:9_05b};1... a7-a6;
{F:B}{B:r2qkb1r/pp1bpppp/2np4/1N4B1/4PPn1/2N5/PPP3PP/R2QKB1R}{S:a7a6}{W:9_05I}Incorrect. Trying to drive the knight back by using the a-pawn is a blunder. After 1... a7-a6?, White doesn't have to withdraw the knight. Instead he can invoke the crushing rejoinder, {S:b5d6}{W:9_05Ia}2. Nb5xd6+!, exploiting the g5-bishop's pin on the {A:Wg5e7}{N1:e7}{W:9_05Ib}e7-pawn. If the e-pawn moves, it exposes the Black queen to capture from g5. But Black doesn't have a choice. He has to take the knight to save his king. So there follows {R}{C}{S:e7d6}{W:9_05Ic}2... e7xd6, enabling White to take Black's queen, {S:g5d8}{W:9_05Id}3. Bg5xd8. White laughs all the way to the chess bank.;
1... Qd8-b6;{F:B}{B:r2qkb1r/pp1bpppp/2np4/1N4B1/4PPn1/2N5/PPP3PP/R2QKB1R}{S:d8b6}{W:9_05C}Correct. Black is advised to unpin his e7-pawn by moving his queen off the {N1:d8e7f6g5h4}{W:9_05Ca}d8-h4 diagonal. This he can do with a gain of time by going to knight-three {C}{S:d8b6}{W:9_05Cb}(1... Qd8-b6), which threatens a queen mate at {A:Bb6f2}{N1:f2}{W:9_05Cc}f2, supported by the {N1:g4}{W:9_05Cd}g4-knight. It also clears {R}{N1:d8}{W:9_05Ce}d8 for Black's king, if it should need a flight square. It won't, however, not after moving the queen to b6.}]

6.
[{F:B}{B:6k1/pp3ppp/1q1pp3/6N1/1P1P2n1/2PQ1PP1/P5Pr/4R1K1}{QB:6. Should Black move the knight or the rook?{W:9_06}{H1:g4}{W:9_06a}{H1:h2}{W:9_06b};move the knight;{F:B}{B:6k1/pp3ppp/1q1pp3/6N1/1P1P2n1/2PQ1PP1/P5Pr/4R1K1}{N1:g4}{W:9_06I}Incorrect. It doesn't matter where Black moves the knight. He's going to have trouble. If he retreats it to {A:Bg4f6}{A:Bg4h6}{N1:f6h6}{W:9_06Ia}f6 or h6, White's king can take the rook at {R}{C}{A:Wg1h2}{N1:h2}{W:9_06Ib}h2 for free. He could try the counterattack {R}{C}{S:g4e5}{W:9_06Ic}1... Ng4-e5, menacing White's queen, and hoping to avoid capture by the {N1:d4}{W:9_06Id}d-pawn, which is pinned to White's king by the queen at {A:Bb6d4}{W:9_06Ie}b6. But White has several answers that gain material. He can break the pin with {R}{C}{S:d3e3}{W:9_06If}2. Qd3-e3, and after {S:e5c4}{W:9_06Ig}2... Ne5-c4, withdraw his queen to e2 {S:e3e2}{W:9_06Ih}(3. Qe3-e2), when both Black's rook and knight are attacked and undefended. Or White could simply play {F:B}{B:6k1/pp3ppp/1q1pp3/4n1N1/1P1P4/2PQ1PP1/P5Pr/4R1K1}{S:e1e5}{W:9_06Ii}2. Re1xe5, sacrificing his rook, knowing that after Black takes it {S:d6e5}{W:9_06Ij}(2... d6xe5), White then garners Black's rook {S:g1h2}{W:9_06Ik}(3. Kg1xh2). In the end, White comes out a piece ahead. By the way, what kind of sacrifice is it, if you know that by sacrificing you're going to win? This (2. Re1xe5) is not a real sacrifice, but rather a pseudo-sacrifice, or a sacrifice in name only.;
move the rook;{F:B}{B:6k1/pp3ppp/1q1pp3/6N1/1P1P2n1/2PQ1PP1/P5Pr/4R1K1}{N1:h2}{W:9_06C}Correct. Black has several rook moves that are worthy of note. For one, he could disengage the rook from attack by withdrawing it to {C}{S:h2h5}{W:9_06Ca}h5. Then, if White takes Black's knight {S:f3g4}{W:9_06Cb}(2. f3xg4), Black's rook takes the White knight {S:h5g5}{W:9_06Cc}(2... Rh5xg5), and it's all even. But why play an okay move when you have much better? Black can punish White's carelessness by {F:B}{B:6k1/pp3ppp/1q1pp3/6N1/1P1P2n1/2PQ1PP1/P5Pr/4R1K1}{S:h2h1}{W:9_06Cd}1... Rh2-h1+!. To this there is only one response, to take the rook {S:g1h1}{W:9_06Ce}(2. Kg1xh1), whereupon Black's knight enters at f2 {S:g4f2}{W:9_06Cf}(2... Ng4-f2+), forking White's king and queen. After the king moves to safety ({S:h1h2}{W:9_06Cg}say 3. Kh1-h2), the knight takes the queen {S:f2d3}{W:9_06Ch}(3... Nf2xd3), and Black has gained a queen for a rook.}]

7.
[{F:W}{B:3q1rk1/pp3bpp/16/1b6/1B3N2/PP4PP/3QR2K}{QB:7. Which piece should White take?{W:9_07}{A:Wb3f7}{H1:f7}{W:9_07a}{A:Wd1d8}{H1:d8}{W:9_07b};the bishop;
{B:3q1rk1/pp3bpp/16/1b6/1B3N2/PP4PP/3QR2K}{S:b3f7}{W:9_07C}Correct. White wins a piece by taking the bishop with check (1. Bb3xf7+). Black can't retake with his rook {S:f8f7}{W:9_07Ca}(1... Rf8xf7), for that hangs the queen {S:d1d8}{W:9_07Cb}(2. Qd1xd8+). So Black's king must do its own dirty work, {B:3q1rk1/pp3Bpp/16/1b6/5N2/PP4PP/3QR2K}{S:g8f7}{W:9_07Cc}1... Kg8xf7, which meets up with the checking fork, {S:d1b3}{W:9_07Cd}2. Qd1-b3+. Wherever Black moves his king, he loses at least his bishop to White's queen {S:b3b4}{W:9_07Ce}(3. Qb3xb4). I say "at least," because he could make the mistake of moving the king to f6 {B:3q1r2/pp3kpp/16/1b6/1Q3N2/PP4PP/4R2K}{S:f7f6}{W:9_07Cf}(2... Kf7-f6), allowing mate {S:b3e6}{W:9_07Cg}(3. Qb3-e6#).;
the queen;{B:3q1rk1/pp3bpp/16/1b6/1B3N2/PP4PP/3QR2K}{S:d1d8}{W:9_07I}Incorrect. Taking the queen (1. Qd1xd8) merely leads to a trade {S:f8d8}{W:9_07Ia}(1... Rf8xd8). Whether White then trades bishops or not {S:b3f7}{W:9_07Ib}(2. Bb3xf7+ {S:g8f7}{W:9_07Ic}Kg8xf7), he will certainly have to make provisions for his attacked rook, spending a tempo to get it to safety. Black is holding his own.}]

8.
[{B:r7/2q2pbk/1pb3pp/2p5/2P5/1P3N2/1B3PPP/R1Q3K1}{QB:8. Which is the better piece for White to take?{W:9_08}{A:Wa1a8}{H1:a8}{W:9_08a}{A:Wb2g7}{H1:g7}{W:9_08b};the rook;
{B:r7/2q2pbk/1pb3pp/2p5/2P5/1P3N2/1B3PPP/R1Q3K1}{S:a1a8}{W:9_08I}Incorrect. Taking the rook (1. Ra1xa8) may seem to win a piece, for after Black takes back {S:c6a8}{W:9_08Ia}(1... Bc6xa8), White trades bishops on g7 {S:b2g7}{W:9_08Ib}(2. Bb2xg7 {S:h7g7}{W:9_08Ic}Kh7xg7) and then gives a queen check at a1 {S:c1a1}{W:9_08Id}(3. Qc1-a1+), forking the Black king and bishop at a8. After Black gets out of check {S:g7h7}{W:9_08Ie}(3... Kg7-h7), White wins the bishop {S:a1a8}{W:9_08If}(4. Qa1xa8). But it doesn't go this way. After White captures the rook {B:r7/2q2pbk/1pb3pp/2p5/2P5/1P3N2/1B3PPP/R1Q3K1}{S:a1a8}{W:9_08Ig}(1. Ra1xa8), Black doesn't take it back yet. Instead he interposes a bishop capture {S:g7b2}{W:9_08Ih}(1... Bg7xb2), which also attacks White's queen. Assuming the queen takes back {S:c1b2}{W:9_08Ii}(2. Qc1xb2), then Black retakes on a8 {S:c6a8}{W:9_08Ij}(3... Bc6xa8). At this point White's queen can still shift to a1, hitting the a-bishop. But that's all the queen attacks, for Black's king is not on g7. So it's not check and White doesn't win anything. (Trading is not winning. Trading is getting the same as you give up. Winning is getting more than you give up, while losing is getting less than you give up.);
the bishop;{B:r7/2q2pbk/1pb3pp/2p5/2P5/1P3N2/1B3PPP/R1Q3K1}{S:b2g7}{W:9_08C}Correct. The winning move is to take Black's g7-bishop (1. Bb2xg7!) first. If Black's king takes back {S:h7g7}{W:9_08Ca}(1... Kh7xg7), then White trades rooks {S:a1a8}{W:9_08Cb}(2. Ra1xa8 {S:c6a8}{W:9_08Cc}Bc6xa8) and follows with a forking queen check {S:c1a1}{W:9_08Cd}(3. Qc1-a1+). After Black ends the check {S:g7h7}{W:9_08Ce}(3... Kg7-h7), White takes the queen-bishop for nothing {S:a1a8}{W:9_08Cf}(4. Qa1xa8). And if Black tries to save himself by answering {B:r7/2q2pbk/1pb3pp/2p5/2P5/1P3N2/1B3PPP/R1Q3K1}{S:b2g7}{W:9_08Cg}1. Bb2xg7 with the interposition {S:a8a1}{W:9_08Ch}1... Ra8xa1, White has two ways to emerge a piece ahead. He can take back with his queen {A:Wc1a1}{N1:a1}{W:9_08Ci}(2. Qc1xa1), which winds up protecting the bishop at g7, preventing Black's king from taking it. Or he could just come backward, taking the rook with the g7-bishop {R}{C}{A:Wg7a1}{N1:a1}{W:9_08Cj}(2. Bg7xa1), getting it out of danger before Black's king can take it.}]

9.
[{F:B}{B:rnb1k1nr/pp2p1bp/5pp1/3q4/3P4/4BN2/PP3PPP/RN1QKB1R}{QB:9. Should Black develop the king-knight or queen-knight?{W:9_09}{A:Bg8h6}{H1:h6}{W:9_09a}{A:Bb8c6}{H1:c6}{W:9_09b};
1... Ng8-h6;
{F:B}{B:rnb1k1nr/pp2p1bp/5pp1/3q4/3P4/4BN2/PP3PPP/RN1QKB1R}{S:g8h6}{W:9_09I}Incorrect. If Black develops the king-knight he has but one move (1... Ng8-h6), for h6 is the only unblocked square available. Unfortunately for Black, this enables White to unleash a devilish double attack, {S:d1c1}{W:9_09Ia}2. Qd1-c1!. Suddenly, Black's h6-knight is threatened by two White pieces, a battery of the {A:Wd2h6}{A:Wc1h6}{N1:h6}{W:9_09Ib}d2-bishop and the c1-queen. Meanwhile, White's queen also menaces the {R}{C}{A:Wc1c8}{N1:c8}{W:9_09Ic}c8-bishop, which is not guarded at all. Black must lose one of them, either the h6-knight or the c8-bishop. Few defenders can dance at two weddings at the same time.;
1... Nb8-c6;{F:B}{B:rnb1k1nr/pp2p1bp/5pp1/3q4/3P4/4BN2/PP3PPP/RN1QKB1R}{S:b8c6}{W:9_09C}Correct. Activating the queen-knight (1... Nb8-c6) is a fine idea, and it doesn't entail any new problems. It also closes the c-file against White's major pieces, and it enables the a8-rook to protect the c8-bishop. Black still must solve his kingside development, but at least he builds the queenside part of his game without losing anything, and there's a lot to be said for this.}]

10.
[{F:B}{B:6k1/5p2/1p2p1n1/1r2b3/3NP3/5PP1/1B1R1K2/8}{QB:10. Should Black take the knight or move his rook?{W:9_10}{A:Be5d4}{H1:d4}{W:9_10a}{H1:b5}{W:9_10b};1... Be5xd4;
{F:B}{B:6k1/5p2/1p2p1n1/1r2b3/3NP3/5PP1/1B1R1K2/8}{S:e5d4}{W:9_10I}Incorrect. Taking the knight (1... Be5xd4) is only a trade, for White takes back with the bishop {S:b2d4}{W:9_10Ia}(2. Bb2xd4). White's game is quite okay after the exchange. Of course, taking back with the rook {S:d4b2}{S:d2d4}{W:9_10Ib}(2. Rd2xd4) loses the bishop to Black's rook {S:b5b2}{W:9_10Ic}(2... Rb5xb2+). After this wrong recapture, White's game is not okay.;
move his rook;{F:B}{B:6k1/5p2/1p2p1n1/1r2b3/3NP3/5PP1/1B1R1K2/8}{N1:b5}{W:9_10C}Correct. Black should move his rook, but where? He'd like to win on {N1:d4}{W:9_10Ca}d4, but this square is held up by two of White's pieces, the bishop and the rook. The answer is to remove both of them with one shot. Black uses his rook to capture the bishop {C}{S:b5b2}{W:9_10Cb}(1... Rb5xb2!). This destroys one of d4's protectors. The other guard (the rook at d2) is lured out of position when it takes back on b2 {S:d2b2}{W:9_10Cc}(2. Rd2xb2). If we assess things at this point, Black has sacrificed the exchange (a rook for a bishop), but this is not the end of the story, for the {N1:d4}{W:9_10Cd}d4-knight is unguarded. So Black takes it for free {C}{S:e5d4}{W:9_10Ce}(2... Be5xd4+), and with check to boot! After White gets out of check, the bishop takes the rook on {A:Bd4b2}{N1:b2}{W:9_10Cf}b2 for free. The aftermath is that Black winds up a bishop ahead.}]

11.
[{F:W}{B:r1bq1rk1/ppp2pp1/5n1p/3p4/3P4/P1N1BQ2/1PP2PPP/R3K2R}{QB: 11. Which way should White castle?{W:9_11}{A:We1g1}{A:Wh1f1}{H1:g1f1}{W:9_11a}{A:We1c1}{A:Wa1d1}{H1:c1d1}{W:9_11b};kingside;{B:r1bq1rkb1/ppp2pp1/5n1p/3p4/3P4/P1N1BQ2/1PP2PPP/R3K2R}{S:e1g1}{S:h1f1}{W:9_11C}Correct. Castling kingside (1. 0-0) is quite reasonable, and it's safe. Black can then develop the queen-bishop, attacking White's queen by {S:c8g4}{W:9_11Ca}1... Bc8-g4, but this can be answered adequately by shifting the queen a square over {S:f3g3}{W:9_11Cb}(2. Qf3-g3). Thereafter, White will probably regain the lost time by moving the king-rook pawn to {A:Wh2h3}{N1:h3}{W:9_11Cc}h3, to drive away the presumptuous bishop.;
queenside;{B:r1bq1rkb1/ppp2pp1/5n1p/3p4/3P4/P1N1BQ2/1PP2PPP/R3K2R}{S:e1c1}{S:a1d1}{W:9_11I}Incorrect. Castling queenside (1. 0-0-0), though often attractive, turns out to be a mistake here, for Black's queen-bishop develops to g4, skewering White's queen and rook {S:c8g4}{W:9_11Ia}(1... Bc8-g4). After White moves his queen to safety {S:f3g3}{W:9_11Ib}(2. Qf3-g3), Back wins the exchange (a rook for a bishop) by taking on d1 {S:g4d1}{W:9_11Ic}(2... Bg4xd1). Note the difference between a pin and a skewer. Generally, both tactics require one friendly unit (the attacker) and two enemy units (the defenders). All three units occupy the same line, either the same rank, the same file, or the same diagonal. A pin prevents the first enemy unit from moving off the line of attack, because this unit shields from capture the enemy unit behind. A skewer does essentially the opposite. Rather than preventing a piece from moving, it practically compels it to do so, which exposes the enemy unit behind it to capture. Another way to view it is with regard to the value of the two attacked enemy units. In a pin, usually the less valuable enemy unit comes first in line, and the more valuable one comes second, shielded from capture by its associate. In a skewer, it's the more valuable unit that appears first in line. It must get out of the way to save itself, thereby exposing the less valuable unit to capture. Regardless, whether it's a pin or a skewer, try to do it to your opponent and don't let it happen to you.}]

12.
[{F:B}{B:rn2kbnr/1bp1pp1p/pp1q2p1/8/2BP4/P1N1P3/1P2NPPP/R1BQ1RK1}{QB:12. Should Black develop his king-knight or threaten mate?{W:9_12}{A:Bg8f6}{H1:f6}{W:9_12a}{A:Bd6c6}{H1:c6}{W:9_12b};1... Ng8-f6;
{F:B}{B:rn2kbnr/1bp1pp1p/pp1q2p1/8/2BP4/P1N1P3/1P2NPPP/R1BQ1RK1}{S:g8f6}{W:9_12C}Correct. Developing the king-knight (1... Ng8-f6) attacks the center and especially observes the squares {N1:d5e4}{W:9_12Ca}d5 and e4. It also brings Black a step closer to castling kingside, which he'll be able to do after completing the fianchetto of his king-bishop {C}{A:Bf8g7}{W:9_12Cb}(Bf8-g7). Finally, it sets up an insidious double attack possibility. If White lets his guard down, Black can transfer his queen to {R}{S:d6c6}{W:9_12Cc}c6. This will threaten mate at {A:Bc6g2}{N1:g2}{W:9_12Cd}g2, as well as the capture of the {A:Bc6c4}{N1:c4}{W:9_12Ce}c4-bishop, so one of the two will have to go unanswered.;
1... Qd6-c6;{B:rn2kbnr/1bp1pp1p/pp1q2p1/8/2BP4/P1N1P3/1P2NPPP/R1BQ1RK1}{S:d6c6}{W:9_12I}Incorrect. Threatening mate by 1... Qd6-c6 loses material, though initially it may seem attractive, for in addition to the mate threat, Black also eyes the capture of the {N1:c4}{W:9_12Ia}c4-bishop. But White confutes both attacks with one play, by butting the bishop in the way at d5 {C}{S:c4d5}{W:9_12Ib}(2. Bc4-d5). This deals with the mate threat by shutting out Black's queen, actually driving it away. Worse than this, however, is that the bishop at {N1:d5}{W:9_12Ic}d5 (protected by the knight at c3) skewers Black's {C}{N1:b7}{A:Wd5b7}{W:9_12Id}queen and b7-bishop. After the queen compulsorily moves to safety, White wins the bishop for free (3. Bd5xb7). It was only a bystander anyway.}]

13.
[{F:W}{B:r2qkbnr/pp1npppp/16/2Qp2b1/4PN2/PP3PPP/RNB1KB1R}{QB:13. How should White take back on d4?{W:9_13}{A:Wc4d4}{H1:d4}{W:9_13a}{A:We3d4}{W:9_13b};1. Qc4xd4;{B:r2qkbnr/pp1npppp/16/2Qp2b1/4PN2/PP3PPP/RNB1KB1R}{S:c4d4}{W:9_13C}Correct. Taking with the queen (1. Qc4xd4) is the more prudent of the two possibilities. It's true that the capture moves the queen again, at least for the third time, but it does threaten Black's bishop at {A:Wd4g4}{N1:g4}{W:9_13Ca}g4. This serves to remove her majesty from the vulnerable c-file without losing a tempo. Besides, it's better to be safe than sorry. Sometimes you have to make concessions, anticipating and warding off your opponent's future threats before they become current problems.;
1. e3xd4;{B:r2qkbnr/pp1npppp/16/2Qp2b1/4PN2/PP3PPP/RNB1KB1R}{S:e3d4}{W:9_13I}Incorrect. Capturing on d4 with the pawn (1. e3xd4) drops material. Black retaliates with {S:a8c8}{W:9_13Ia}1... Ra8-c8, which attacks White's {A:Bc8c4}{N1:c4}{W:9_13Ib}queen as well as the {R}{C}{A:Bc8c1}{N1:c1}{W:9_13Ic}c1-bishop behind it. This is a skewer, and there's no way that White can move his queen to safety without exposing the bishop to Black's c8-rook. Before taking on d4, White should have looked ahead and foreseen this looming threat.}]

14.
[{F:B}{B:8/1p3p1k/nP4p1/6P1/r6P/8/7B/3K2R1}{QB:14. Should Black take a pawn or check?{W:9_14}{A:Ba4h4}{H1:h4}{W:9_14a}{A:Ba4a1}{H1:a1}{W:9_14b};1... Ra4xh4;
{F:B}{B:8/1p3p1k/nP4p1/6P1/r6P/8/7B/3K2R1}{S:a4h4}{W:9_14I}Incorrect. Black can gain a pawn by taking on h4 (1... Ra4xh4), but this gives White some chances to stay in the game. He might, for instance, be able to establish his bishop on the {N1:a1b2c3d4e5f6g7h8}{W:9_14Ia}a1-h8 diagonal (say by going to e5, and then f6, {A:Wh2e5}{A:We5f6}{W:9_14Ib}if necessary or desirable), hoping somehow to sneak his rook around to {R}{N1:h8}{W:9_14Ic}h8 to render mate. This is not a forced possibility, but it gives White a purpose for living. If you have a lost position, and you don't intend to resign, you should develop a strategy that helps you maintain the fight. You might, for example, look for ways to cause your opponent difficulties. If there are roadblocks to be set, it's always possible that he might fail to get around or through them. Another thing to think about are possible checkmates -- mates that can be conceived with the forces you have available. Even if, in the current position, your opponent can defend against these contingencies, by staying mindfully attentive you might still catch your opponent if he lets his guard down. If you don't try to set him up, hoping for him to go wrong, what's the point of continuing at all? Finally, whatever the circumstances on the board, whether you're winning, losing, or drawing, there's a proper strategy. Find it and use it for guidance.;
1... Ra4-a1+;{F:B}{B:8/1p3p1k/nP4p1/6P1/r6P/8/7B/3K2R1}{S:a4a1}{W:9_14C}Correct. Checking along the back rank (1... Ra4-a1+) is a killer. Not because it wins the rook at g1. It doesn't, for the g1-rook is guarded by the h2-bishop. But rather because it forces White's king to the second rank. After {S:d1c2}{W:9_14Ca}2. Kd1-c2, Black skewers king and bishop by {S:a1a2}{W:9_14Cb}2... Ra1-a2+. White will have to move his king out of check, and Black's rook captures the bishop for free.}]

15.
[{F:B}{B:6k1/5p2/p3n1p1/q2b4/N2p4/3PP3/1P2KP2/3Q1B2}{QB:15. Should Black move his knight or bishop?{W:9_15}{A:Be6g5}{H1:g5}{W:9_15a}{A:Bd5f3}{H1:f3}{W:9_15b};1... Ne6-g5;
{F:B}{B:6k1/5p2/p3n1p1/q2b4/N2p4/3PP3/1P2KP2/3Q1B2}{S:e6g5}{W:9_15I}Incorrect. Moving the knight (1... Ne6-g5) reveals a pernicious threat, to protect a bishop check at {A:Bd5f3}{N1:f3}{W:9_15Ia}f3 that skewers White's king and queen, while also threatening mate! So even if White were to remove his queen from the d1-h5 diagonal by going to c2 {R}{C}{S:d1c2}{W:9_15Ib}(2. Qd1-c2), Black still ices the enemy by {S:d5f3}{W:9_15Ic}2... Bd5-f3#. But White can save himself with the counterattacking advance, {F:B}{B:6k1/5p2/p5p1/q2b2n1/N2p4/3PP3/1P2KP2/3Q1B2}{S:e3e4}{W:9_15Id}2. e3-e4. This blocks out Black's bishop all together, while gaining time by threatening to capture it. And if the bishop retreats to c6 {S:d5c6}{W:9_15Ie}(2... Bd5-c6), White should still be kicking after, {S:b2b3}{W:9_15If}3. b2-b3, protecting the knight at {N1:a4}{W:9_15Ig}a4 and more or less holding the fort.;
1... Bd5-f3+;{F:B}{B:6k1/5p2/p3n1p1/q2b4/N2p4/3PP3/1P2KP2/3Q1B2}{S:d5f3}{W:9_15C}Correct. The crusher is 1... Bd5-f3+!. This is a sacrifice, and it must be accepted {S:e2f3}{W:9_15Ca}(2. Ke2xf3), for the bishop skewers White's king and queen. Besides, White doesn't have another legal move! However, after the bishop is taken by the king, Black has yet another skewer, transferring the queen from one edge to the other, {S:a5h5}{W:9_15Cb}(2... Qa5-h5+), and this one leaves White crestfallen. After the king gets out of check {S:f3g2}{W:9_15Cc}(say 3. Kf3-g2), Black captures White's queen {A:Bh5d1}{N1:d1}{W:9_15Cd}(3... Qh5xd1) for free. Actually, it could end up even worse than this if White flees the check by scurrying his king up to e4 {R}{C}{S:g2e4}{W:9_15Ce}(3. Kf3-e4). This brash response is disposed of by {S:h5f5}{W:9_15Cf}3... Qh5-f5#, which is mate, for d4 is guarded by Black's knight.}]

16.
[{F:W}{B:r1bq1rk1/1pppbppp/p1n2n2/4p3/B3P3/5N2/PPPP1PPP/RNBQR1K1}{QB:16. Should White capture the knight or advance the c-pawn one square?{W:9_16}{A:Wa4c6}{H1:c6}{W:9_16a}{A:Wc2c3}{H1:c3}{W:9_16b};1. Ba4xc6;{B:r1bq1rkb1/1pppbppp/p1n2n2/4p3/B3P3/5N2/PPPP1PPP/RNBQR1K1}{S:a4c6}{W:9_16C}Correct. Taking the knight (1. Ba4xc6) is tactically on the money. No matter how Black takes back (let's say he takes back with the d-pawn, {S:d7c6}{W:9_16Ca}1... d7xc6), White on the next move will be able to swipe the king-pawn {S:f3e5}{W:9_16Cb}(2. Nf3xe5) without consequence. This is because, by taking the knight on move one, White has undermined the king-pawn's support. This kind of tactic is also known as "removing the guard" or "removing the defender.";
1. c2-c3;{B:r1bq1rkb1/1pppbppp/p1n2n2/4p3/B3P3/5N2/PPPP1PPP/RNBQR1K1}{S:c2c3}{W:9_16I}Incorrect. Advancing the queen-bishop pawn to c3 (1. c2-c3) is a fairly typical move in similar situations. It not only prepares for the two-square advance of White's {N1:d2}{W:9_16Ia}d-pawn, it also gives the {N1:a4}{W:9_16Ib}a4-bishop a retreat, if it should need one. Nevertheless, here it is a perfunctory play, which doesn't take into account a sudden opportunity. Black's king-pawn is inadequately protected, and by removing the guard {B:r1bq1rkb1/1pppbppp/p1n2n2/4p3/B3P3/5N2/PPPP1PPP/RNBQR1K1}{S:a4c6}{W:9_16Ic}(1. Ba4xc6), White can win it {S:f3e5}{W:9_16Id}(2. Nf3xe5). Even a "good" move (1. c2-c3) can be rendered "bad" when there's something clearly better (1. Ba4xc6).}]

17.
[{F:B}{B:1kr4r/pbp1qp2/1p6/6pp/1b2P3/2N3N1/PP2QPPP/2R2RK}{QB:17. Should Black take a knight or attack one?{W:9_17}{A:Bb4c3}{H1:c3}{W:9_17a}{A:Bh5h4}{H1:h4}{W:9_17b};1... Bb4xc3;
{F:B}{B:1kr4r/pbp1qp2/1p6/6pp/1b2P3/2N3N1/PP2QPPP/2R2RK}{S:b4c3}{W:9_17C}Correct. White's king-pawn is attacked twice (by the {N1:e7b7}{W:9_17Ca}queen and b7-bishop) and defended three times {N1:c3e2g3}{W:9_17Cb}(by the queen and two knights). But this superiority can be overturned by capturing on c3 (1... Bb4xc3), which removes one of the king-pawn's supporters. After White takes back {C}{S:c1c3}{W:9_17Cc}(2. Rc1xc3, or even {A:Wb2c3}{N1:c3}{W:9_17Cd}2. b2xc3), Black then drives away another protector, the g3-knight, by advancing the h-pawn to h4 {R}{C}{S:h5h4}{W:9_17Ce}(2... h5-h4). The knight can intrude on the fifth rank {S:g3f5}{W:9_17Cf}(3. Ng3-f5), attacking Black's queen, but Black can counter by taking the king-pawn {S:e7e4}{W:9_17Cg}(3... Qe7xe4). This capture also menaces mate at g2, since the queen is diagonally supported by the b7-bishop. To stave off mate and simultaneously save his hanging queen, White will have to trade queens, leaving Black a pawn ahead for the endgame.;
1... h5-h4;{F:B}{B:1kr4r/pbp1qp2/1p6/6pp/1b2P3/2N3N1/PP2QPPP/2R2RK}{S:h5h4}{W:9_17I}Incorrect. This advance (1... h5-h4)does indeed get rid of one of the e-pawn's defenders, but after, {S:g3f5}{W:9_17Ia}2. Ng3-f5, Black is unable to capture on e4 with his queen because the {N1:c3}{W:9_17Ib}c3-knight still guards {A:Wc3e4}{N1:e4}{W:9_17Ic}e4. This is because the c3-knight still exists. The proper sequence is for Black to take on {R}{N1:c3}{W:9_17Id}c3 first, eliminating the c3-knight, and then to push the {N1:h5}{W:9_17Ie}h-pawn. It's not enough to find the right moves. You must also play them in the right order.}]

18.
[{F:B}{B:rnb2rk1/1pp1qppp/1p3n2/4p1B1/1P2P3/P4N2/2P2PPP/R2QKB1R}{QB:18. Which rook should Black move?{W:9_18}{H1:f8}{W:9_18a}{H1:a8}{W:9_18b};the king-rook;{F:B}{B:rnb2rk1/1pp1qppp/1p3n2/4p1B1/1P2P3/P4N2/2P2PPP/R2QKB1R}{S:f8d8}{W:9_18I}Incorrect. Seizing the d-file with the king-rook (1... Rf8-d8) is surely a salubrious idea. It attacks White's queen and compels an answer. But it misses out on an opportunity by being too "mechanical." That is, it's played because, as a rule of thumb, a player should seize an open file whenever he can do so with a gain time. But this is a general principle, which doesn't necessarily have application in the situation at hand. Still, White must respond to 1... Rf8-d8 with care. To  avoid the stinger {S:a8a3}{W:9_18Ia}(Ra8xa3 and {S:e7b4}{W:9_18Ib}Qe7xb4+), he'll have to move his queen to either {F:B}{B:rnbr2k1/1pp1qppp/1p3n2/4p1B1/1P2P3/P4N2/2P2PPP/R2QKB1R}{A:Wd1b1}{A:Wd1c1}{N1:b1c1}{W:9_18Ic}b1 or c1, both of which are a little awkward because White's queen remains on the home rank. This might later on interfere with the process of connecting the rooks. Even so, White remains in the game after either deployment (after either Qd1-c1 or Qd1-b1). So maybe Black should move the other rook.;
the queen-rook;{F:B}{B:rnb2rk1/1pp1qppp/1p3n2/4p1B1/1P2P3/P4N2/2P2PPP/R2QKB1R}{S:a8a3}{W:9_18C}Correct. Moving the queen-rook (1... Ra8xa3!) begins an undermining combination that plunders a pawn. If White takes back {S:a1a3}{W:9_18Ca}(2. Ra1xa3), Black's queen barrels through at b4 {S:e7b4}{W:9_18Cb}(2... Qe7xb4+). This is a fork, which attacks the {A:Bb4a3}{N1:a3}{W:9_18Cc}a3 rook and, at the same time, {A:Bb4e1}{N1:e1}{W:9_18Cd}checks White's king. After White gets out of check {R}{C}{S:g5d2}{W:9_18Ce}(say 3. Bg5-d2), Black gobbles the a3-rook {S:b4a3}{W:9_18Cf}(3... Qb4xa3). In the end, Black gains two pawns.}]

19.
[{F:B}{B:rnbqr1k1/ppp2ppp/1b6/3P4/NP2n3/P3BN2/2P2PPP/R2QKB1R}{QB:19. Should Black take the bishop or move the knight?{W:9_19}{A:Bb6e3}{H1:e3}{W:9_19a}{A:Be4f2}{H1:f2}{W:9_19b};1... Bb6xe3;
{F:B}{B:rnbqr1k1/ppp2ppp/1b6/3P4/NP2n3/P3BN2/2P2PPP/R2QKB1R}{S:b6e3}{W:9_19I}Incorrect. Taking the bishop (1... Bb6xe3) is not so bad, for after White takes back {S:f2e3}{W:9_19Ia}(2. f2xe3), Black has a number of targets to shoot at, including the pawn at {N1:d5e3}{W:9_19Ib}d5 and the pawn at e3. Both of these come under fire after the retreat {S:e4f6}{W:9_19Ic}2... Ne4-f6. (Actually, Black isn't retreating, he's advancing backward.) But as good as exchanging on e3 is, Black has even better {F:B}{B:rnbqr1k1/ppp2ppp/1b6/3P4/NP2n3/P3BN2/2P2PPP/R2QKB1R}{A:Be4f2}{N1:f2}{W:9_19Id}(1... Ne4xf2), and this is what he should play.;
1... Ne4xf2;{F:B}{B:rnbqr1k1/ppp2ppp/1b6/3P4/NP2n3/P3BN2/2P2PPP/R2QKB1R}{S:e4f2}{W:9_19C}Correct. The undermining blast, 1... Ne4xf2, forks queen and rook while removing the protection for the e3-bishop. White must take back {S:e1f2}{W:9_19Ca}(2. Ke1xf2), after which Black bulldozes ahead with {S:b6e3}{W:9_19Cb}2... Bb6xe3+ (taking on e3 with the rook, {S:e3b6}{S:e8e3}{W:9_19Cc}2... Re8xe3, encounters White's undermining capture, {A:Wa4b6}{N1:b6}{W:9_19Cd}3. Na4xb6, which removes the rook's guard). Since trying to flee toward the kingside {F:B}{B:rnbqr1k1/ppp2ppp/8/3P4/NP6/P3bN2/2P2KPP/R2Q1B1R}{S:f2g3}{W:9_19Ce}(3. Kf2-g3) loses quickly via the queen check, {S:d8d6}{A:Bd6g3}{N1:g3}{W:9_19Cf}3... Qd8-d6+, White is reduced to moving the King onto the e-file {F:B}{B:rnbqr1k1/ppp2ppp/8/3P4/NP6/P3bN2/2P2KPP/R2Q1B1R}{S:f2e2}{W:9_19Cg}(3. Kf2-e2,  for instance). This sets up a discovery from Black's rook at e8, which enables Black to acquire at least the exchange by {S:e3d4}{W:9_19Ch}3... Be3-d4+. White can save his king {S:e2d2}{W:9_19Ci}(say 4. Ke2-d2), but he loses the rook at a1 {S:d4a1}{W:9_19Cj}4... Bd4xa1) in exchange for Black's dark-square bishop {S:d1a1}{W:9_19Ck}(5. Qd1xa1).}]

20.
[{F:B}{B:7r/kpQ5/1p5r/1P2pP2/P2qB1p1/3P2P1/5P2/2R3K1}{QB:20. Should Black move a rook or sac the queen?{W:9_20}{A:Bh8h7}{H1:h7}{W:9_20a}{A:Bd4e4}{H1:e4}{W:9_20b};1... Rh8-h7;
{F:B}{B:7r/kpQ5/1p5r/1P2pP2/P2qB1p1/3P2P1/5P2/2R3K1}{S:h8h7}{W:9_20I}Incorrect. White is threatening mate at {N1:b7}{W:9_20Ia}b7, so guarding the b-pawn by 1... Rh8-h7 makes sense. (This is an x-ray defense, in that the rook protects the square {W:9_20Ib}b7 through the White queen.) But this misses an immediate win. In fact, even though Black's move was wrong, it still kept the winning idea in the air, so White just can't play any old defensive move with his queen. He must be sure to retreat the queen {C}{S:c7c4}{W:9_20Ic}to c4, which also bolsters the menaced e4-bishop, preventing Black from playing a decisive sacrifice {A:Bd4e4}{N1:e4}{W:9_20Id}(2... Qd4xe4). The things we have to do to avoid defeat.;
1... Qd4xe4;{F:B}{B:7r/kpQ5/1p5r/1P2pP2/P2qB1p1/3P2P1/5P2/2R3K1}{S:d4e4}{W:9_20C}Correct. Black has a decisive blow, 1... Qd4xe4!.  This removes the defender of the {N1:h1}{W:9_20Ca}h1-square. If White takes Black's queen {C}{S:d3e4}{W:9_20Cb}(2. d3xe4), Black forces mate in two moves by starting with a rook check on h1, {S:h6h1}{W:9_20Cc}2... Rh6-h1+ {S:g1g2}{W:9_20Cd}3. Kg1-g2 {S:h8h2}{W:9_20Ce}Rh8-h2#. And if White doesn't take Black's queen, how does he intend to prevent murder on the cathedral square of h1?}]

21.
[{F:B}{B:rnb1kb1r/ppp2ppp/8/3qp3/4N3/5Q2/PPPP1PPP/R1B1K1NR}{QB:21. Should Black defend the f-pawn or move it?{W:9_21}{A:Bc8e6}{H1:e6}{W:9_21a}{A:Bf7f5}{H1:f5}{W:9_21b};1... Bc8-e6;
{F:B}{B:rnb1kb1r/ppp2ppp/8/3qp3/4N3/5Q2/PPPP1PPP/R1B1K1NR}{S:c8e6}{W:9_21C}Correct. Defending the f-pawn (1... Bc8-e6) secures {N1:f7}{W:9_21Ca}f7, while doing two other useful things. It develops a new piece, and more importantly it guards the queen,  which otherwise is sitting out there unprotected, ripe for exploitation. Sometimes by playing a decent general move you accidentally protect yourself against a specific unforeseen threat. Such is life, and such is chess.;
1... f7-f5;{F:B}{B:rnb1kb1r/ppp2ppp/8/3qp3/4N3/5Q2/PPPP1PPP/R1B1K1NR}{S:f7f5}{W:9_21I}Incorrect. The advance, 1... f7-f5, is very aggressive. It tries to drive away White's knight so that Black has the option of trading queens. The problem is that it doesn't deal with White's threat, and this is to move the {N1:e4}{W:9_21Ia}e4-knight with a gain of time, unveiling a winning discovery to Black's queen. The debacle is brought about by checking on f6 {C}{S:e4f6}{W:9_21Ib}(2. Ne4-f6+). True, Black can take the knight for free {S:g7f6}{W:9_21Ic}(2... g7xf6), but he can't find the time to save his queen, which falls victim to White's, {S:f3d5}{W:9_21Id}3. Qf3xd5. Blind aggression (1... f7-f5) once again proves to be blind.}]

22.
[{F:W}{B:r1b1kb1r/ppppq1pp/5n2/4nPB1/16/PPP2PPP/RN1QKBNR}
{QB:22. Should White move the queen or attack Black's queen?{W:9_22}{A:Wd1e2}{H1:e2}{W:9_22a}{A:Wg5f6}{H1:f6}{W:9_22b};1. Qd1-e2;
{B:r1b1kb1r/ppppq1pp/5n2/4nPB1/16/PPP2PPP/RN1QKBNR}{S:d1e2}{W:9_22C}Correct. Black has a threat. It's to move the {N1:e5}{W:9_22Ca}e5-knight, giving a discovery to White's king, from Black's queen. By placing White's own queen on e2 (1. Qd1-e2), White prevents the discovered check. The e5-knight can still be moved, but afterward Black's queen will not be giving check. True, placing White's queen on e2, where it hampers the development of the {N1:f1}{W:9_22Cb}f1-bishop, is typically unpleasant, but something has to be done to stop the discovery. Besides, Black has a similar problem with his own queen. It too blocks in a bishop, the one occupying {N1:f8}{W:9_22Cc}f8. It's usually better to be uncomfortable, but alive, than comfortable, but chessically dead.;
1. Bg5xf6;{B:r1b1kb1r/ppppq1pp/5n2/4nPB1/16/PPP2PPP/RN1QKBNR}{S:g5f6}{W:9_22I}Incorrect. The move 1. Bg5xf6 seems to stop the action. It involves the taking of a piece in a way that attacks the enemy threatener. It therefore appears to gain time on Black's queen, and it's this threat to Black's queen that fools White into expecting a recapture on the square {N1:f6}{W:9_22Ia}f6. But the discovery still works, and Black ignores the threat to his own queen to garner White's king by the discovery, {C}{S:e5f3}{W:9_22Ib}1... Ne5-f3#. This is a special kind of discovered check. It's called "double check" because two Black pieces check White's king, the queen at {A:Be7e1}{A:Bf3e1}{N1:e1}{W:9_22Ic}e7 (the stationary unit) and the knight at f3 (the moving unit). Curiously, both the stationary and moving units are capturable by White's forces, but neither can be taken because the remaining one would still be giving check. In fact, there is no way for White to avoid the capture of his king on the next move. So it's checkmate and the game is over.}]

23.
[{B:r1bqr3/pppnbkpp/8/1N1p4/2P2n2/P3P3/1P3PPP/R2QKBNR}{QB:23. Should White take the pawn or the knight?{W:9_23}{A:Wc4d5}{H1:d5}{W:9_23a}{A:We3f4}{H1:f4}{W:9_23b};1. c4xd5;{B:r1bqr3/pppnbkpp/8/1N1p4/2P2n2/P3P3/1P3PPP/R2QKBNR}{S:c4d5}{W:9_23C}Correct. Taking the queen-pawn (1. c4xd5) gains a pawn, but White is already down a piece. This was the price he had to pay for drawing the Black king {N1:f7}{W:9_23Ca}to f7, where it's more exposed. After taking on d5, it's not clear that White has enough for his sacrificed material, but Black is not yet out of the woods, and there are still problems to solve. For example, if Black isn't careful, White may shortly be able to get away with capturing the knight {N1:f4}{W:9_23Cb}on f4.;
1. e3xf4;{B:r1bqr3/pppnbkpp/8/1N1p4/2P2n2/P3P3/1P3PPP/R2QKBNR}{S:e3f4}{W:9_23I}Incorrect. Trying to regain the sacrificed piece by taking the f4-knight (1. e3xf4) leads to trouble. It opens the {N1:e1e2e3e4e5e6e7e8}{W:9_23Ia}e-file, exposing White's king to a deadly double check. Black makes one move and mates, {C}{S:e7b4}{W:9_23Ib}1... Be7-b4#. This issues two checks (from the {A:Bb4e1}{A:Be8e1}{N1:e1}{W:9_23Ic}bishop and the rook), and that's mate. It's the awesomeness of this juggernaut force that has led many pundits to refer to double check as "the most powerful move in chess."}]

24.
[{B:rn1qkb1r/p1ppp2p/1p3nP1/7Q/3P4/3B4/PPP2PbP/RNB1K1NR}{QB:24. Should White advance a pawn or capture one?{W:9_24}{A:Wg6g7}{H1:g7}{W:9_24a}{A:Wg6h7}{H1:h7}{W:9_24b};1. g6-g7+;{B:rn1qkb1r/p1ppp2p/1p3nP1/7Q/3P4/3B4/PPP2PbP/RNB1K1NR}{S:g6g7}{W:9_24I}Incorrect. Advancing the pawn (1. g6-g7+) looks very inviting. It gives a discovered check to Black's king. {A:Wh5e8}{N1:e8}{W:9_24Ia}Black can answer the threat by taking White's queen {R}{C}{S:f6h5}{W:9_24Ib}(1... Nf6xh5), but the loss of the queen is only temporary. White regains it and more by taking the rook on h8, promoting to a new queen {S:g7h8}{P:WQh8}{W:9_24Ic}(2. g7xh8/Q). In the process, White has won and lost a queen, and gained a rook. Black then acquires a rook himself {S:g2h1}{W:9_24Id}(2... Bg2xh1), but the story isn't over, and White's attack may still win the day. The problem with this continuation is that it misses out on a greater one, and therefore it's the wrong answer.;
1. g6xh7+;{B:rn1qkb1r/p1ppp2p/1p3nP1/7Q/3P4/3B4/PPP2PbP/RNB1K1NR}{S:g6h7}{W:9_24C}Correct. White has a forced mate in two moves. First he takes on h7 {S:g6h7}{W:9_24Ca}(1. g6xh7+), unleashing a discovered check from White's queen {A:Wh5e8}{N1:e8}{W:9_24Cb}. The capture also destroys the protector of g6, the h7-pawn. White's queen goes down in the transaction {R}{C}{S:f6h5}{W:9_24Cc}(1... Nf6xh5), but another diagonal power (the d3-bishop) assumes the reigns, delivering an oblique mate at g6, {S:d3g6}{W:9_24Cd}2. Bd3-g6#. When the pieces are working harmoniously, there's always one ready to replace another.}]

25.
[{B:rnbqk2r/pp3ppp/3b1n2/3p4/3Pp3/1QN1P3/PP3PPP/R1B1KBNR}{QB:25. Should White move the queen-bishop or take a pawn?{W:9_25}{A:Wc1d2}{H1:d2}{W:9_25a}{A:Wc3d5}{H1:d5}{W:9_25b};1. Bc1-d2;
{B:rnbqk2r/pp3ppp/3b1n2/3p4/3Pp3/1QN1P3/PP3PPP/R1B1KBNR}{S:c1d2}{W:9_25C}Correct. Moving the queen-bishop (1. Bc1-d2) develops a new piece, while strengthening the {N1:a5b4c3d2e1}{W:9_25Ca}a5-e1 diagonal against possible checks. It also arms White with the threat to capture the {N1:d5}{W:9_25Cb}d-pawn, which on this move was not feasible because of the counter check on b4 from Black's f8-bishop{A:Bd6b4}{N1:b4}{W:9_25Cc}. A little preparation can go a long way. It might even threaten to win a pawn.;
1. Nc3xd5;{B:rnbqk2r/pp3ppp/3b1n2/3p4/3Pp3/1QN1P3/PP3PPP/R1B1KBNR}{S:c3d5}{W:9_25I}Incorrect. Capturing the queen-pawn (1. Nc3xd5) is a blunder. It wins a pawn, but it loses the knight to {S:f6d5}{W:9_25Ia}1... Nf6xd5. White can't follow through by taking back {S:b3d5}{W:9_25Ib}(2. Qb3xd5), for he runs into the discovery, {S:d6b4}{W:9_25Ic}2... Bd6-b4+. This is a check, and must be respected. After White answers it, Black can capture White's greedy queen for free {S:c1d2} {S:d8d5}{W:9_25Id}(2... Qd8xd5). Instead of taking on {B:rnbqk2r/pp3ppp/3b1n2/3p4/3Pp3/1QN1P3/PP3PPP/R1B1KBNR}{N1:d5}{W:9_25Ie}d5 immediately, White needs to prepare this capture by safeguarding the {N1:a5b4c3d2e1}{W:9_25If}a5-e1 diagonal with {S:c1d2}{W:9_25Ig}1. Bc1-d2. Then he's ready for whatever life has to offer.}]

26.
[{B:2kr1bnr/pppb1ppp/3q4/4n3/4Q3/2P2N2/PP3PPP/RNB1KB1R}{QB:26. Should White take on e5 with the queen or the knight?{W:9_26}{A:We4e5}{H1:e5}{W:9_26a}{A:Wf3e5}{W:9_26b};1. Qe4xe5;
{B:2kr1bnr/pppb1ppp/3q4/4n3/4Q3/2P2N2/PP3PPP/RNB1KB1R}{S:e4e5}{W:9_26C}Correct. Taking on e5 with the queen (1. Qe4xe5) is an obvious blunder, for Black simply pins the queen to its king by {S:d8e8}{W:9_26Ca}1... Rd8-e8. Generally, you shouldn't commence operations on the king-file with your king still on its original square. If the center opens, the regal one may have to abdicate before its time. But as bad as this capture (1. Qe4xd5) is, it's better than the other choice (1. Nf3xe5), which loses the game by force, and in three moves to boot.;
1. Nf3xe5;{B:2kr1bnr/pppb1ppp/3q4/4n3/4Q3/2P2N2/PP3PPP/RNB1KB1R}{S:f3e5}{W:9_26I}Incorrect. Capturing on e5 with the knight (1. Nf3xe5) is apparently risky, but White probably figures that he can survive by giving back the knight -- if he has to. So White doesn't fear the possibility of the knight getting pinned by {A:Bd8e8}{W:9_26Ia}1... Rd8-e8. The problem is that Black doesn't try to regain the material at all. Instead he goes for bigger game, forcing mate with {R}{S:d6d1}{W:9_26Ib}1... Qd6-d1+!!. What choice does White have other than to take the queen, {S:e1d1}{W:9_26Ic}2. Ke1xd1? But this places the king on a vulnerable square (d1), where it's in line with Black's {N1:d8}{W:9_26Id}d8-rook. Mate is then fashioned by giving the right double check, {S:d7g4}{W:9_26Ie}2... Bd7-g4+. (The wrong double check is {A:Bd7a4}{N1:a4}{W:9_26If}2... Bd7-a4+.) White has two ways to go after 2... Bd7-g4+. He can sidle the king over to its original square {R}{C}{S:d1e1}{W:9_26Ig}(3. Kd1-e1), but then mate is delivered by the rook {S:d8d1}{W:9_26Ih}(3... Rd8-d1#), which is protected by the bishop. If he instead moves the king up to c2 {S:d1d8}{S:e1c2}{W:9_26Ii}(3. Kd1-c2), Black pronounces mate with the bishop {S:g4d1}{W:9_26Ij}(3... Bg4-d1#), which is supported by the rook. This is great teamwork, and it's all set up by sacrificing the queen to give an unanswerable discovery.}]

27.
[{F:B}{B:rnb1k2r/pp2qppp/1bp2n2/3pQ3/1P2P3/P1NB1N2/2P2PPP/R1B1K2R}{QB:27. Should Black avoid the queen trade or seek it?{W:9_27}{A:Bc8e6}{H1:e6}{W:9_27a}{A:Be7e5}{H1:e5}{W:9_27b};1... Bc8-e6;
{F:B}{B:rnb1k2r/pp2qppp/1bp2n2/3pQ3/1P2P3/P1NB1N2/2P2PPP/R1B1K2R}{S:c8e6}{W:9_27I}Incorrect. Many of us are overly fond of the queen, so we take every opportunity to avoid its exchange, sometimes even when the act of trading it confers advantage. But this is carrying a prejudice too far, as does the unexciting development, 1... Bc8-e6. It's a satisfactory move, all right. It develops toward the center, secures {N1:d5}{W:9_27Ia}d5, and accomplishes its aim, the avoidance of a queen trade. But it's this very queen trade that gives Black the win. Go back to the drawing board and play the other move.;
1... Qe7xe5;{F:B}{B:rnb1k2r/pp2qppp/1bp2n2/3pQ3/1P2P3/P1NB1N2/2P2PPP/R1B1K2R}{S:e7e5}{W:9_27C}Correct. Exchanging queens (1... Qe7xe5) may seem to wither away Black's attack, but actually it fuels it. After White's compulsory recapture, {S:f3e5}{W:9_27Ca}2. Nf3xe5, Black issues the humiliating fork, {S:b6d4}{W:9_27Cb}2... Bb6-d4. This attacks both {A:Bd4e5}{A:Bd4c3}{N1:e5c3}{W:9_27Cc}White knights, as well as the rook at {R}{C}{A:Bd4a1}{N1:a1}{W:9_27Cd}a1 by skewer, insuring the gain of at least a piece. How often would a grandmaster trade queens just to win a healthy piece? All the time.}]

28.
[{F:B}{B:r5k1/pp3ppp/1b6/P3r3/3q1NQ1/3P4/1P3PPP/R1B2RK1}{QB:28. Should Black attack the pinned knight or take a pawn?{W:9_28}{A:Bg7g5}{H1:g5}{W:9_28a};1... g7-g5;
{F:B}{B:r5k1/pp3ppp/1b6/P3r3/3q1NQ1/3P4/1P3PPP/R1B2RK1}{S:g7g5}{W:9_28I}Incorrect. It's true that White's knight at f4 is pinned to its queen by {A:Bd4f4}{N1:f4}{W:9_28Ia}Black's queen, but advancing the king-knight pawn (1... g7-g5) doesn't guarantee winning the knight. For one, it's very risky to move the pawns in front of your own king. Moreover, once it's placed on g5, the pawn is also pinned, by White's queen to Black's king. Therefore it can't yet capture on f4 anyway, which gives White the time for a spark of salvation, such as the thrust, {R}{C}{S:h2h4}{W:9_28Ib}2. h2-h4. This attacks the {A:Wh4g5}{N1:g5}{W:9_28Ic}g-pawn while also giving the White king a flight square, in case it needs one. By the way, it does.;
take a pawn;{F:B}{B:r5k1/pp3ppp/1b6/P3r3/3q1NQ1/3P4/1P3PPP/R1B2RK1}{W:9_28C}Correct. Black should take a pawn, all right. But not with the idea of gaining material (say, {A:Be5a5}{N1:a5}{W:9_28Ca}1... Re5xa5). Rather for the purpose of delivering mate in two moves, which is achieved by the brilliancy, {R}{C}{S:d4f2}{W:9_28Cb}1... Qd4xf2+!. It's mate on the next turn however White replies. Either White moves his king to the corner {S:g1h1}{W:9_28Cc}(2. Kg1-h1), allowing the queen to mate by taking the unprotected rook {S:f2f1}{W:9_28Cd}(2... Qf2xf1#). Or White's rook captures the queen {F:B}{B:r5k1/pp3ppp/1b6/P3r3/5NQ1/3P4/1P3qPP/R1B2RK1}{S:f1f2}{W:9_28Ce}(2. Rf1xf2), which leads to a back rank checkmate from the e5-rook {S:e5e1}{W:9_28Cf}(2... Re5-e1#). Why can't White's {N1:f2}{W:9_28Cg}f2-rook retreat to block the check? Because it's pinned by the {A:Bb6f2}{W:9_28Ch}b6-bishop. Yes, the pin can be mightier than the sword.}]

29.
[{F:B}{B:r1bqkb1r/pp1ppp1p/5Pp1/1B6/8/2p5/PPPP1PPP/R1BQK2R}{QB:29. Should Black take a pawn or attack a piece?{W:9_29}{A:Bc3b2}{H1:b2}{W:9_29a}{A:Bd8b6}{H1:b6}{W:9_29b};1... c3xb2;
{F:B}{B:r1bqkb1r/pp1ppp1p/5Pp1/1B6/8/2p5/PPPP1PPP/R1BQK2R}{S:c3b2}{W:9_29I}Incorrect. Black could try to gain a pawn by capturing on b2 (1... c3xb2), but how does he continue after White takes back {S:c1b2}{W:9_29Ia}(2. Bc1xb2)? If he follows with the capture of the f6-pawn {S:e7f6}{W:9_29Ib}(2... e7xf6), White obtains counterplay by checking with his queen {S:d1e2}{W:9_29Ic}(3. Qd1-e2). Then, regardless how Black blocks the check on e7 (whether by {A:Bd8e7}{W:9_29Id}3... Qd8-e7 or {R}{C}{S:f8e7}{W:9_29Ie}3... Bf8-e7), {W:9_29If}White's b2-bishop will be able to take on f6 {S:b2f6}{W:9_29Ig}(4. Bb2xf6), and White is doing fine. Note that the piece Black uses to block on e7 can't recapture on f6 because it's pinned by White's {A:We2e7}{N1:e7}{W:9_29Ih}queen to Black's king. A pin to the king is called an absolute pin. The pinned unit can't move off the line no matter what. A pin to any piece other than the king is known as a relative pin. In the case of a relative pin, the pinned unit can move off the line if the defender is willing to accept the consequences. After 1... c3xb2  2. Bc1xb2, the only other thing that Black might try is to position the queen at b6 {F:B}{B:r1bqkb1r/pp1ppp1p/5Pp1/1B6/16/PBPP1PPP/R1BQK2R}{S:d8b6}{W:9_29Ii}(2... Qd8-b6), skewering the bishop on b5 and the bishop on {A:Bb6b2}{N1:b5b2}{W:9_29Ij}b2. This is a terrific idea, but the timing is all wrong, and White can save himself by capturing on e7 {R}{C}{S:f6e7}{W:9_29Ik}(3. f6xe7), attacking the {A:We7f8}{N1:f8}{W:9_29Il}f8-bishop while discovering an attack from the b2-bishop to the {R}{C}{A:Wb2h8}{N1:h8}{W:9_29Im}h8-rook. In this line, Black is clearly not in the dominant position.;
1... Qd8-b6;{F:B}{B:r1bqkb1r/pp1ppp1p/5Pp1/1B6/8/2p5/PPPP1PPP/R1BQK2R}{S:d8b6}{W:9_29C}Correct. The sly placement, 1... Qd8-b6, wins a piece. White finds himself facing a satanic skewer, to the {A:Bb6b2}{N1:b2b5}{W:9_29Ca}b5-bishop and the b2-pawn behind the bishop. If White moves his bishop to safety (say, {R}{C}{S:b5c4}{W:9_29Cb}2. Bb5-c4), Black captures the b-pawn {S:c3b2}{W:9_29Cc}(2... c3xb2), backed up by the queen. It's a fork, and there's no satisfactory way to salvage both the rook at a1 and the bishop at c1. For example, the counter-pin, {S:a1b1}{W:9_29Cd}3. Ra1-b1, is met directly by {S:b2c1}{P:BQc1}{W:9_29Ce}3... b2xc1/Q, making a new queen and going up at least a piece. Taking Black's b6-queen {S:b1b6}{W:9_29Cf}(4. Rb1xb6) doesn't help at this point, for after he trades the remaining queens {S:c1d1}{W:9_29Cg}(4... Qc1xd1+ {S:e1d1}{W:9_29Ch}5. Ke1xd1), Black's fortunes rise by the addition of a rook via the recapture, {S:a7b6}{W:9_29Ci}5... a7xb6. But after, {F:B}{B:r1bqkb1r/pp1ppp1p/5Pp1/1B6/8/2p5/PPPP1PPP/R1BQK2R}{S:d8b6}{W:9_29Cj}1... Qd8-b6, White does have another way he can try to avoid material loss. He could guard his bishop on b5. But however he does this (let's say by {S:d1e2}{W:9_29Ck}2. Qd1-e2), Black kicks the bishop with the a-pawn {S:a7a6}{W:9_29Cl}(2... a7-a6), and the same problems are still there. Nor does it help if White continues with the capture, {S:f6e7}{W:9_29Cm}3. f6xe7, for Black is able to recapture on e7 {S:f8e7}{W:9_29Cn}(3... Bf8xe7), and with careful play should escape additional injury. Meanwhile, white still drops a piece.}]

30.
[{F:B}{B:8/1k6/2pq3p/3BR3/pp3p1P/P4P2/KP2QP2/6r1}{QB:30. Should Black move a pawn or take a piece?{W:9_30}{A:Bb4b3}{H1:b3}{W:9_30a};1... b4-b3+;{F:B}{B:8/1k6/2pq3p/3BR3/pp3p1P/P4P2/KP2QP2/6r1}{S:b4b3}{W:9_30I}Incorrect. On the surface, Black has a very menacing pawn move, {S:b4b3}{W:9_30Ia}1... b4-b3+. White's king would then have no place to go. But he does have a bishop guarding b3, and it's an extra bishop, so it could be sacrificed to break the force of Black's attack {S:d5b3}{W:9_30Ib}(2. Bd5xb3 {S:a4b3}{W:9_30Ic}a4xb3 {S:a2b3}{W:9_30Id}3. Ka2xb3). After this foray, White's king is no more vulnerable than Black's, but White has two additional pawns, and this might soon begin to mean something, especially if Black is forced to trade queens. For instance, after {S:d6d1}{W:9_30Ie}3... Qd6-d1+ {S:e2d1}{W:9_30If}4. Qe2xd1 {S:g1d1}{W:9_30Ig}Rg1xd1, the ending is probably won for White.;
take a piece;{F:B}{B:8/1k6/2pq3p/3BR3/pp3p1P/P4P2/KP2QP2/6r1}{W:9_30C}Correct. Taking a piece is the right idea, but which piece? You saw incisively if you played, {S:d6d5}{W:9_30Ca}1... Qd6xd5+!, removing the guard. This annihilates the protector of the {N1:b3}{W:9_30Cb}b3-square, so that after White takes back {C}{S:e5d5}{W:9_30Cc}(2. Re5xd5), the advance {S:b4b3}{W:9_30Cd}2... b4-b3# meets up with no resistance. It's mate, and that's that.}]