//Tutorial file

TITLE "CHESS MOVES"

BEGIN SUB-MODULE - "Review All Levels"

BEGIN NAMES
"Introduction"
"Level 1:  The Basics"
"Level 2:  Kings and Pawns"
"Level 3:  Queens and Rooks"
"Level 4:  Minor Piece Endings"L
"Level 5:  Mating Configurations"
"Level 6:  Basic Combinations"
"Level 7:  Roots of Combinations"
"Level 8:  Double Attacks"
"Level 9:  Sacrifices"
"Level 10: Strategy"
END NAMES

//===================================================================
//First chapter:  Introduction
//===================================================================
BEGIN CHAPTER 0

NOTATION ALGEBRAIC

BOARD 64 WHITE
"This tutorial takes you from simple positions to more complex strategic 
situations in 10 levels."
OK

"At each level, you demonstrate mastery of the concepts by answering a 
challenge question, where you make the move you think is the correct answer."
OK

"There are more than 200 positions in all.  Use this building-block method 
at your own pace.  As a beginner, you can learn basics.  As you advance, 
you can learn multi-move combinations."
OK

"You can also use Chess Tutor as a 'refresher course' over time, since 
the positions are interesting as well as instructional."
OK

"When the 'Move' button is active, you can view a sequence of moves.  
Click the Move button to see the next move.  After you view all moves 
in the sequence, the Move button is inactive (ghosted)."
OK

BOARD rnbqkbnr/pppppppp/32/PPPPPPPP/RNBQKBNR WHITE
MOVELIST "e4 e5 Nf3 Nc6 Bb5"
"Try clicking the Move button a few times and watch the first moves of the 
Ruy Lopez opening."
OK

END CHAPTER

//===================================================================
//Second chapter:  Level 1:  The Basics
//===================================================================
BEGIN CHAPTER 1

BOARD 64 WHITE 
//"The Basics"
//OK

"What is checkmate?  What is stalemate?  What is zugzwang?"
OK

BOARD R3k3/8/4K3/40 BLACK
"Start with this most basic checkmate."
OK

BOARD R3k3/8/4K3/32/1rr5 BLACK
MOVELIST "Rb8 Rxb8 Rc8 Rxc8"
"The Rooks can only delay checkmate two more moves with Rb8 and Rc8."
OK

BOARD R5k1/5ppp/8/b7/b7/8/6K1/1rr5 BLACK
MOVELIST "Rb8 Rxb8 Rc8 Rxc8 Bd8 Rxd8 Be8 Rxe8"
"The Rooks and Bishops can only delay checkmate four more moves."
OK

BOARD 5k2/8/4K3/32/R7 WHITE
"Challenge #1:  What single move can White make to force mate on the 
following move?  (Mate in 2)."
CHALLENGE Rg1 "That's right!"
OK

"The correct move is 1. Rg1 Ke8   2. Rg8++"
MOVELIST "Ke8 Rg8"
OK

BOARD 5K1k/6Pp/48 BLACK
"A Pawn mate."
OK

BOARD 5K1k/5N1p/48 BLACK
"A Knight mate."
OK

BOARD 5K1k/7p/40/2B3R1 WHITE
"Either Bishop or Rook can mate:  1. Bb2++ or  1. Rg8++"
OK

BOARD R3K2k/7p/48 WHITE
CHALLENGE Kf7 "That is correct!"
"Challenge #2:  How does White mate?"
MOVELIST "Kf7"
OK

BOARD 4k3/R7/3K4/40 WHITE
"A mate often depends on forcing the opponent to make a move."
OK

MOVELIST "Rb7 Kf8 Ke6 Kg8 Kf6 Kh8 Kg6 Kg8 Rb8" 
"Sometimes you simply wait:  1. Rb7! Kf8   2. Ke6 Kg8  The Black King can no 
longer run away.  3. Kf6 Kh8   4. Kg6 Kg8   5. Rb8++"
OK

BOARD 8/4k3/R7/3K4/32 WHITE
"The same procedure lets White push the opponent back another rank.  
1. Rb6! Kf7   2. Ke5, etc."
MOVELIST "Rb6 Kf7 Ke5"
OK

BOARD 6k1/R7/40/7K WHITE
"Challenge #3:  What is the fastest mate for White?"
CHALLENGE Kg2 "That's right!"
OK

MOVELIST "Kf8 Kf3 Ke8 Ke4 Kd8 Kd5 Kc8 Kc6 Kb8 Re7 Ka8 Kb6 Kb8 Re8" 
"The correct sequence is to advance the King on the diagonal, since Black's 
best defense is to move toward b8."
OK

BOARD 3k4/R7/2K5/40 WHITE
MOVELIST "Rh7 Ke8 Rb7 Kd8 Ra7"
"Now, by losing a move, White can bring about the basic mating sequence in 
the previous positions.  1. Rh7 Ke8  2. Rb7 Kd8  3. Ra7."
OK

BOARD 24/4N3/8/7p/8/5K1k WHITE
MOVELIST "Ng4 h2 Nf2"
"Being forced to move when you would rather not is called 'zugzwang.'  
Here, White forces Black to move a Pawn when Black would be safe without 
moving.  1. Ng4 h2   2. Nf2++"
OK

BOARD 24/5N2/8/7p/5K2/7k WHITE
MOVELIST "Ng3+ Kh2 Nf1+ Kh1"
"If White could 'wait' it could mate.  But after:  1. Ng3+ Kh2   2. Nf1+ Kh1, 
White has no 'waiting' move and Black draws."
OK

BOARD 4k3/4P3/4K3/40 WHITE
MOVELIST "Kf6 Kd7"
"If it's Black's move, it's stalemate.  If White moves, 1. Kf6(d6)   Kd7(f7), 
Black loses."
OK

END CHAPTER

BOARD 64 WHITE

//===================================================================
//Third chapter:  Level 2:  Kings and Pawns
//===================================================================

BEGIN CHAPTER 2

BOARD 64 WHITE
"What is 'the opposition?'  What are 'Pawn advantages?'  What is 'the square?'"
OK

BOARD 4k3/16/4PK2/32 WHITE
"In Pawn endings, move the King in front of the passed pawn." 
OK

MOVELIST "Ke6 Kd8 Kf7"
"1. Ke6!  Kd8(f8)   2. Kf7(d7) and the Pawn has a paved road to a Queen."
OK

BOARD 4k3/8/4P3/5K2/32 WHITE
MOVELIST "Kf6 Kf8 e7 Ke8"
"No matter who moves first, it's a draw.  If it is White's move:  1. Kf6  
Kf8   2. e7+ Ke8  Draw as shown already.  Black to move would play 
1. ... Ke7.  White must either stalemate the King or lose the Pawn."
OK

BOARD 24/2K1p3/4P1k1/24 WHITE
"White must choose between d6 and d5 to attack the enemy Pawn." 
OK

MOVELIST "Kd6 Kf4 Kd5"
"1. Kd6! Kf4   2. Kd5 and Black must leave its Pawn."
OK

BOARD 16/3k4/1p3p2/1P3P2/3K4/16 WHITE
"The 'opposition' means being in a position to make the other King 'step 
aside.'  1. Kd4! Kc6(e6)   2. Ke5(c5), winning a Pawn."
OK

BOARD 8/p7/1p5k/1P6/4K3/24 WHITE
"Challenge #4:  How does White win?"
CHALLENGE Kd5 "That is correct!"
OK

"The right idea is to advance to b7 and win the two Black Pawns."
OK

BOARD 8/p7/1p2k3/1P6/4KP2/24 WHITE
MOVELIST "f5+ Kf6 Kd5"
"If the White King's path is blocked, an 'outside' passed Pawn (f4) can open 
it:  1. f5+ Kf6   2. Kd5 and White wins."
OK

BOARD 8/p7/1p2k3/1P4p1/4K3/5PP1/16 WHITE
MOVELIST "f4 gxf4 gxf4"
"Unlike the 'backward' Pawn at a7, White's f3 Pawn can move.  So you can 
arrive at the preceding position:  1. f4! gxf4   2. gxf4"
OK

BOARD 8/p7/1p2k3/1P6/4KPp1/6P1/16 WHITE
"White gets a 'protected passed Pawn' if Black played 1. ... g4 in the 
previous position.  If Black plays ... Kxg3, then White can play f5 and go on 
to Queen."
OK

BOARD 8/p7/1p6/1Pk5/4KPp1/6P1/16 BLACK
MOVELIST "Kxb5 f5 Kc6"
"The White Pawn at b5 is 'isolated' and can be won if not protected by the 
White King.  If:  1. ... Kxb5   2. f5 Kc6! stops the White Pawn."
OK

BOARD 8/p7/1p6/2k2P2/4K1p1/6P1/16 WHITE
"But if Black had played 2. ... Kc5?, Black can stop the Pawn only if the 
Pawn advances alone."
OK

MOVELIST "f6 Kd6 f7 Ke7"
"The White Pawn is lost."
OK

BOARD 8/p7/1p1k1P2/8/4K1p1/6P1/16 WHITE
MOVELIST "Kf5 Kd7 Kg6"
"The White King now supports the Pawn to the Queening square with:  
4. Kf5! Kd7   5.Kg6."
OK

BOARD 2PPPP2/p1PPPP2/1pPPPP2/1kPPPP2/6p1/6P1/8/6K1 WHITE
GHOST WHITE PAWN c5
GHOST WHITE PAWN c6
GHOST WHITE PAWN c7
GHOST WHITE PAWN c8
GHOST WHITE PAWN d5
GHOST WHITE PAWN d6
GHOST WHITE PAWN d7
GHOST WHITE PAWN d8
GHOST WHITE PAWN e5
GHOST WHITE PAWN e6
GHOST WHITE PAWN e7
GHOST WHITE PAWN e8
GHOST WHITE PAWN f6
GHOST WHITE PAWN f7
GHOST WHITE PAWN f8
"The square formed by the diagonal c5-f8 is the area the Black King must get 
into to stop the Pawn at f5."
OK

BOARD 2PPPP2/p1PPPP2/1pPPPP2/1kPPPP2/4K1p1/6P1/16 BLACK
GHOST WHITE PAWN c5
GHOST WHITE PAWN c6
GHOST WHITE PAWN c7
GHOST WHITE PAWN c8
GHOST WHITE PAWN d5
GHOST WHITE PAWN d6
GHOST WHITE PAWN d7
GHOST WHITE PAWN d8
GHOST WHITE PAWN e5
GHOST WHITE PAWN e6
GHOST WHITE PAWN e7
GHOST WHITE PAWN e8
GHOST WHITE PAWN f6
GHOST WHITE PAWN f7
GHOST WHITE PAWN f8
"Sometimes just 'getting into the square' is not good enough.  In this 
position, because of the White King:  1. ... Kc6! is the right way; 
1. ... Kc5? is wrong."
OK

BOARD 8/p7/1p6/1k3P2/4K1p1/6P1/16 BLACK
MOVELIST "Kc6 f6 Kd7 Kf5 Ke8"
"If 1. ... Kc6  2. f6 Kd7!  3. Kf5 Ke8, the Black King gains the square f8."
OK

BOARD 16/4k3/p7/1p2KPp1/1P4P1/16 WHITE
MOVELIST "f5 Kf6 Kf4 a4 bxa4 b3 Ke4"
"Here White must watch the 'square' formed by the diagonal b1-d3.  If 
1. f5+ Kf6   2. Kf4? a4!   3. bxa4 b3, then Black can Queen."
OK

BOARD 16/4k3/p7/1p2KPp1/1P4P1/16 BLACK
MOVELIST "a4 bxa4 b3 Kd3"
"If it's Black's move:  1. ... a4   2. bxa4 b3   3. Kd3 and White wins the 
Pawn."
OK

BOARD 24/p4k2/1p3Pp1/1P4P1/K7/8 WHITE
"Can you identify the following?  1. Two isolated Pawns.  2. A protected 
passed Pawn.  3. A backward Pawn."
OK

GHOST WHITE PAWN b3
GHOST BLACK PAWN g4
"The 'isolated' Pawns are b3 and g4."
OK

NOGHOST b3
NOGHOST g4
GHOST WHITE PAWN f4
"The 'protected passed Pawn' is f4."
OK

NOGHOST f4
GHOST BLACK PAWN a5
"The 'backward Pawn' is a5."
OK

END CHAPTER   
BOARD 64 WHITE

//===================================================================
//Fourth chapter:  Level 3:  Queens and Rooks
//===================================================================

BEGIN CHAPTER 3

"When both sides Queen, Special King Positions, How the Rook attacks and 
defends."
OK

BOARD 24/p4k2/1p3Pp1/1P4P1/K7/8 BLACK
MOVELIST "Ke4 Kb2 Kf3 f5 Kg3 f6 Kh2 f7 g3 f8Q g2"
"Black's only chance is to attack the g3 Pawn:  1. ... Ke4   2. Kb2 Kf3   
3. f5 Kxg3   4. f6 Kh2   5. f7 g3   6. f8(Q) g2  Can White stop the Pawn?"
OK

BOARD 5Q2/16/p7/1p6/1P6/1K4pk/8 WHITE
MOVELIST "Qf2 Kh1 Qh4 Kg1 Kc2"
"1. Qf2! Kh1   2. Qh4+ Kg1   3. Kc2.  White systematically drives the King 
in front of the Pawn and the White King keeps moving closer."
OK

BOARD 4Q3/40/K4pk1/8 WHITE
MOVELIST "Qe2 Kh1 Qxf2"
"But what if it's a Black Pawn on the f (or c) file?  Black has a 'stalemate' 
defense:  1. Qe2 Kh1!   2. Qxf2 stalemate."
OK

BOARD 48/K3Qp2/7k WHITE
MOVELIST "Kb2 Kg1 Qg4 Kh1 Qh3 Kg1 Qg3 Kh1"
"What if the White King tries to approach?  2. Kb2 Kg1  Of course, this was 
possible on the first move, too.  3. Qg4+ Kh1   4. Qh3+ Kg1   5. Qg3+ Kh1  
Black avoids Kf1 and White can make no progress."
OK 

BOARD 8/7p/8/2K5/8/5k2/P7/8 BLACK
MOVELIST "h5 a4 h4 a5 h3 a6 h2 a7 h1Q a8Q+ Kf4 Qxh1"
"Even if Black moves first and queens first, White queens with check, 
'skewering' the King and Queen.  1. ... h5   2. a4 h4   3. a5 h3 4. a6 h2   
5. a7 h1(Q)   6. a8(Q)+ and   7. Qxh1."
OK 

BOARD K7/7p/24/5k2/1P6/8 WHITE
MOVELIST "b4 h5 b5 h4 b6 h3 b7 h2 b8Q h1Q Qb7+ Kf4 Qxh1" 
"White to move doesn't queen with check, but has a similar 'skewer' to 
follow.  1. b4 h5   2. b5 h4   3. b6 h3   4. b7 h2   5. b8(Q) h1(Q)   
6. Qb7+ and 7. Qxh1."
OK

BOARD 8/7p/8/4K1k1/16/1P6/8 WHITE
MOVELIST "b4 h5 b5 h4 b6 h3 b7 h2 b8Q h1Q Qg8+ Kh4 Qh8+ Kg4 Qxh1"
"Sometimes it takes another check to set up the skewer.  1. b4 h5   
2. b5 h4   3. b6 h3   4. b7 h2   5. b8(Q) h1(Q)   6. Qg8+ Kh4 7Qh7(8)+ and 
8. Qxh1."
OK

BOARD 24/5K2/16/Q1p5/3k4 WHITE
MOVELIST "Ke4 c1Q Kd3 Qf4 Qc2 Ke1 Qe2" 
"In a few cases, the Black Pawn cannot be captured before queening, yet is 
thereafter defenseless to protect against mate:   1. Ke4! c1(Q)  
2. Kd3 Qf4   3. Qc2+ Ke1   4. Qe2++"
OK

BOARD K7/2P5/8/2k5/16/2p5/8 BLACK
"Challenge #5:  How does Black draw?"
CHALLENGE Kb4 "That's right!"
OK

MOVELIST "c8Q Kb3"
"1. ... Kb4.  Black draws, not with 1. ... c1(Q)   2. c8 (Q)+, but with 
1. ... Kb4 (c4)  2. c8(Q) Kb3 and the Black King can't be prevented from 
getting to a1, with the 'stalemate position.'"
OK

BOARD 5rk1/1P6/24/6p1/8/1KR5 WHITE
MOVELIST "Rc8 g2 Rxf8+ Kg7 Rg8+ Kxg8 b8Q+ Kg7 Qg3"
"How the Rook helps a Pawn to queen:   1. Rc8 g2   2. Rxf8+ Kg7   3. Rg8+!  
Simplest, to end all opposition:   3. ... Kxg8   4. b8(Q)+ and 5. Qg3."
OK

BOARD 8/7k/1P6/8/6r1/8/K2R4/8 BLACK
MOVELIST "Rb4"
"For the defense, note how Black must get behind (not in front of) the Pawn:  
1. ... Rb4!   (NOT 1. ... Rg7   2. Rc2!   3. Rc7.)"
OK

BOARD 8/6k1/4r3/1P6/8/K7/3R4/8 WHITE
MOVELIST "Rf2 Re4 b6 Re6 Rb2"
"The Rook can also cut off the enemy King's approach.  The White King can 
support the Pawn's advance:   1. Rf2! Re4 (Trying to cut off the White 
King.)   2. b6 Re6   3. Rb2, but not 3. b7 Ra6+ and 4. Rb6+, winning the Pawn."
OK

BOARD 1R6/1P3k2/32/1r6/4K3 WHITE
MOVELIST "Rh8 Rxb7 Rh7+ Kg6 Rxb7"
"The Rook sometimes can take advantage of being in front of the Pawn if the 
Rook can check safely, or set up a skewer such as:  1. Rh8! Rxb7   2. Rh7+ 
and   3. Rxb7"
OK

BOARD 1R6/1P1k2p1/8/6p1/6P1/1r5P/8/K7 WHITE
MOVELIST "Rg8 Rxb7 Rxg7+ Kd8 Rxg5"
"Or the Rook can give up the Pawn to win additional material:  1. Rg8! Rxb7   
2. Rxg7+ and   3. Rxg5"
OK

BOARD 5K2/2k2P2/32/4r3/5R2 WHITE
MOVELIST "Kg7 Rg2+ Kf6"
"If the King can avoid checks, the Pawn will queen:  1. Kg7 Rg2+   2. Kf6"
OK

BOARD 3k1K2/5P2/32/6r1/4R3 WHITE
MOVELIST "Re4 Kd7 Rd4+ Kc6 Ke7 Re2+ Kf6 Rf2+ Kg6 Rg2+ Kf5 Rf2+ Rf4"
"The White Rook can also 'build a bridge' to end checks when the Rook can't 
get behind the Pawn:   1. Re4 Kd7   2. Rd4+ Kc6  3. Ke7 Re2+   4. Kf6 Rf2+   
5. Kg6 Rg2+   6. Kf5 Rf2+  7. Rf4 wins.  This is the 'Lucena' position."
OK

BOARD K7/P4k2/32/1r6/4R3 WHITE
"Challenge #6:  How does White win?"
CHALLENGE Rc1 "That's right!"
OK

//BOARD K7/P4k2/32/1r6/2R5 BLACK
MOVELIST "Ke7 Rc8 Kd7 Rb8"
"The Rook must get to b8.  1. Rc1 (or h1) Ke7   2. Rc8 Kd7  3. Rb8   After a 
number of checks, the King will escape to c5  (NOT 2. Rc7+? Kd6
3. Rb7 Rh2! and   4. Kb8? Rh8++)"
OK

END CHAPTER   
BOARD 64 WHITE
OK

//===================================================================
//Fifth chapter:  Level 4:  Minor Piece Endings
//===================================================================

BEGIN CHAPTER 4

//"Minor Piece Endings"
//OK

BOARD 4r1k1/2P5/16/7B/16/1K6 WHITE
MOVELIST "Bd8"
"l. Bd8 wins, as the Bishop cuts off the Rook from the queening square."
OK

BOARD 6rk/2P5/3N4/32/1K6 WHITE
MOVELIST "Nf7+ Kg7 Nd8"
"1. Nf7+ Kg7   2. Nd8 wins.  Whereas,  1. c8(Q) wins the Rook, but only draws."
OK

BOARD 8/2P4k/16/K7/4n3/16 BLACK
MOVELIST "Nd5 c8Q Nb6+ Kb5 Nxc8"
"The Knight is a surprisingly good defender against a Pawn about to queen:   
1. ... Nd5!   2. c8(Q) Nb6+ and   3. ... Nxc8"
OK

BOARD 7k/3P1n2/4N3/3K4/32 WHITE
MOVELIST "Kc5 Kg8 Kb6 Kh8 Kc7 Kg8 Nd8 Ne5 Nc6 Nxd7"
"It's difficult to drive a Knight away from the queening square:  
1. Kc5 Kg8   2. Kb6 Kh8   3. Kc7 Kg8   4. Nd8 Ne5 and   5. ... Nxd7"
OK

BOARD 8/4PK1k/24/2n5/16 BLACK
"The Knight alone can prevent King and Pawn from queening safely:"
OK

MOVELIST "Nb5 Ke6 Nc7 Kd6 Ne8 Kd7 Nf6"
"1. ... Nb5! (NOT 1. ... Ne4   2. Ke6 followed by   3. Ke5, winning)   
2. Ke6 ... (Otherwise, Nd6+)   2. ... Nc7+   3. Kd6 ... (If 3. Kd7 Nd5 
wins the Pawn because of Nf6+)   3. ... Ne8+   4. Kd7 Nf6+ draw."
OK

"This strategy will not work with an enemy Rook Pawn, because the Knight 
cannot move on both sides of the Pawn."
OK

BOARD 2b5/2P1K1k1/24/1B6/16 WHITE
MOVELIST "Be6 Ba6 Kd8 Kf8 Bc8 Be2 Bb7 Bg4 Bc6"
"The Bishop can be driven from the queening square, unlike the Knight.  
1. Be6 Ba6   2. Kd8 Kf8   3. Bc8 Be2   4. Bb7 Bg4   5. Bc6, followed by Bd7."
OK

BOARD 2n5/4k3/1P6/16/2b1K3/2b1P3/8 WHITE
MOVELIST "b7 Bd4 Kd2"
"But the Knight is sometimes vulnerable on the back rank:  1. b7! Bd4+   
2. Kd2! ... (NOT 2. Kxd4 Na7   3. Kc5 Nc6   4. Kxc6 Be4+.)  The Pawn has 
two queening squares after the correct move to Kd2."
OK

BOARD 6k1/6b1/P4p2/4p3/24/6K1 BLACK
"Challenge #7:  Can Black, on the move, stop the Pawn?  Show how."
CHALLENGE Bf8 "That's right!"
OK

"The Bishop can stop the Pawn, with 1. ... Bf8 2. a7 Bc5+.  But not 
1. ... Bh6 2. Kf2!"
MOVELIST "a7 Bc5"
OK

BOARD 3n4/16/p7/P7/8/5KBk/8 WHITE
MOVELIST "Bd5"
"The Bishop is a dominating force against an inactive Knight:  1. Bd5!  
The Knight is trapped and will be won by the King."
OK

BOARD 2k5/16/p7/P6n/7n/2BB4/3K4 WHITE
MOVELIST "Be1 Nf3 Bf5"
"The two Bishops are deadly on an open board:  1. Be1 Nf3  2. Bf5+, winning 
a piece." 
OK

BOARD 8/4b3/2k2p1p/2p2Pp1/2K1N1P1/8/2P5/8 WHITE
MOVELIST "c3"
"In closed positions, with the Knight on a safe square and the opposing 
Bishop on the same color as the Pawns, the Knight is often dominant:   
1. c3! waiting."
OK

BOARD 8/4b3/2k2p1p/2p2Pp1/2K1N1P1/2P5/8/8 BLACK
MOVELIST "Kb6 Kd5 Kb5 Ke6"
"Even though Black is a Pawn up, Black must now either lose a Pawn by 
moving the Bishop, or allow the White King to advance by moving the King.  
A typical sequence might be:   1. ... Kb6   2. Kd5 Kb5   3. Ke6, winning."
OK

BOARD 8/6Pk/2P2n2/8/K5pp/8/4B3/8 WHITE
"Challenge #8:  How does White win?"
CHALLENGE c7 "1. c7.  That part is easy." 
OK

BOARD 8/2P3Pk/5n2/8/K5pp/8/4B3/8 BLACK
MOVELIST "Nd5 g8Q Kxg8 Bc4"
"Did you get:  1. c7 Nd5 (NOT 1. ... Nd7   2. Kb5(a5))?  2. g8(Q)+! Kxg8   
3. Bc4!  The Knight has the power to fork; the Bishop to pin.  Note that   
1. g8(Q)+ is wrong because of Nxg8   2. c7 Ne7."
OK

END CHAPTER   
BOARD 64 WHITE
OK

//===================================================================
//Sixth chapter:  Level 5:  Mating Configurations
//===================================================================

BEGIN CHAPTER 5 

BOARD 64 WHITE
//"Mating Configurations"
//OK

"Major piece mates.  Minor piece mates.  With pins and double-checks."
OK

BOARD rnbqkbnr/ppppp2p/8/5ppQ/24/4K3 WHITE
"One of the basic checkmates in the opening, shown without the rest of the 
White force.  The move Qh5+ (or Qh4+ by Black) is always dangerous when the 
f Pawn is moved, even more-so when the g Pawn is also moved!"
OK

BOARD 3qk3/5Q2/16/2B5/16/4K3 WHITE
"In schematic form, another basic checkmate in the opening.  Although it's 
overly optimistic to aim for this mate in the first few moves, it often 
occurs as a threat when 1. Qf3 or 1. Qh5 also attacks a Black piece -- 
a double threat."
OK

BOARD 5rk1/7Q/24/3B4/8/4K3 WHITE
"Against the castled Black King, this is a similar common threat (or 
checkmate, as here).  Note that, if a Black Pawn were at g7, the King would 
have a 'flight' at f7."
OK

BOARD 5rk1/3n3Q/8/6N1/24/4K3 WHITE
"A White Knight at g5 also supports the same checkmate."
OK

MOVELIST "Qh5 Rd8 Qf7 Kh8 Qh7"
"Note that Black has two common defenses to this type of mate, if the Queen 
is at h5 threatening 2. Qh7++:   1. ... Nf6, guarding h7, or    1. ... Rf6, 
giving the King a 'flight' at f8.  Note that   1. ... Rd8 fails because of   
2. Qf7+ and   3. Qh7++"
OK

BOARD 5r1k/6p1/4Q1P1/32/4K3 WHITE
MOVELIST "Qh3 Kg8 Qh7"
"Advancing the g Pawn creates many threats against the castled King, 
especially if it reaches g6:   1. Qh3+ Kg8   2. Qh7++"
OK

BOARD 3r1rk1/3n1pp1/24/3B3Q/8/6K1 BLACK
"Challenge #9:  There are five ways to prevent the threatened checkmate at 
h7.  You are Black.  What move also attacks a White piece?"
CHALLENGE Nf6 "That is correct!"
OK

"The correct move is 1. ... Nf6, which attacks the Bishop at d3."
OK

BOARD 3q2k1/6Q1/3b4/24/1B6/4K3 WHITE
"Another strong mating alliance is the Queen and Bishop teaming up on the 
'long diagonal.'  The typical defenses are moving Bishop or Queen to f8."
OK

BOARD 6rk/8/7Q/32/4K3 WHITE
"The Queen performs many elegant checkmates because of her ability to control 
'flight' squares.  This mate is called the 'epaulette' mate if it occurs 
toward the center of the board with another Black Rook next to the King."
OK

BOARD Q1k5/2pb4/40/4K3 WHITE
"This check occurs often, if only as a threat, when the King castles on the 
Queenside.  Castling Queenside is considered more risky than on the Kingside 
because of greater territory to defend on the a file."
OK

BOARD 6kR/5pp1/40/4K2R WHITE
"Doubled Rooks are more than twice as powerful as two Rooks operating 
independently."
OK

BOARD 5rk1/6RR/40/4K3 WHITE
"On rank 7, their natural home because that's where the enemy Pawns are, 
Rooks that are doubled often threaten this mate."
OK

BOARD 7k/40/7R/4K1R1 WHITE
"When the Rooks 'undouble' they usually catch the King in this clean mate.  
Sacrifices clearing away the Pawns at g7 and h7 are aimed at this type of 
checkmate."
OK

BOARD 4k3/5R1R/16/r7/r7/p7/K7 WHITE
"Challenge #10:  Can you find a winning move for White?"
CHALLENGE Rb7 "That is correct!"
OK

"Full points for 1. Rb7, which mates next move:  1. ... Ra8   2. Rh8++"
OK

"Moves like   1. Rc7 or   1. Rfg7 are answered by   1. ... Kd8 or Kf8."
OK

BOARD 5rk1/7p/8/5N2/16/1B6/4K3 WHITE
MOVELIST "Nh6"
"Control of the 'long diagonal' by a Bishop leads to many types of mates.  
This one is elegant:   1. Nh6++  (NOT 1. Ne7+ Kf7)"
OK

BOARD 6rk/5Npp/40/4K3 WHITE
"A famous Knight mate, the 'smothered.'"
OK

BOARD 3qkb2/3pp3/16/4N3/8/4Q3/4K3 WHITE
"White has a choice of mates here.  You already saw   1. Qh5++.  But isn't 
the smothered mate prettier?  1. Nd6++  Note the pin of the e Pawn."
OK

BOARD 2kr4/3b4/B7/8/5B2/16/4K3 WHITE
"Another example of a splashy mate on a Queenside castled King.  Bishops 
multiply in value with the extra space of the a file."
OK
  
BOARD 7k/7p/16/2B5/8/1B6/4K3 WHITE
"A mate that's repeated in many areas of the board.  This arrangement of the 
Bishops is the closest equivalent to the doubling of the Rooks."
OK

BOARD 3qkb2/8/3p4/4N3/2B5/2N5/8/4K3 WHITE
"Challenge #11:  Bishops and Knights sometimes perform heroically together.  
What would you do as White?"
CHALLENGE Bf7 "That's right!"
OK

MOVELIST "Ke7 Nd5"
"In schematic form, this is the famous 'Legal's Mate.'  It emphasizes the 
vulnerability of f7 (or f2 for White).  With a White Knight at c3, it's a 
spectacular mate:  1. Bf7+ Ke7   2. Nd5++"
OK

BOARD 7k/7R/5N2/32/4K3 WHITE
"Rook and minor pieces collaborate frequently in mates.  The Knight's 'magic 
square' is f6 (or f3, c6, c3)."
OK

BOARD 6kR/5p2/32/1B6/4K3 WHITE
"Bishop and Rook are especially dangerous with the Bishop on the famous 
'long diagonal.'  The 'fianchettoed Bishop' at b2, b7, g7, or g2 is the 
easiest way for a Bishop to control this diagonal."
OK

BOARD 2bkn3/2p5/32/3B4/3RK3 WHITE
MOVELIST "Bg5"
"The minor pieces often collaborate with 'double checks,' a chief feature of 
which is that no enemy piece can interpose.  If there are no King flights, 
it's mate, as here:  1. Bg5++"
OK

BOARD 6bk/4p1Np/32/1B6/4K3 WHITE
MOVELIST "Ne6"
"In a 'discovered check,' the leading piece (here the Knight) can often 
perform other duties.  In this case the Knight 'shuts off' the Black Pawn:   
1. Ne6++"
OK

BOARD 6nb/R4P1k/7q/32/4K3 WHITE
"Challenge #12:  How does White use a discovered check to win (or mate)?"
CHALLENGE f8N "That is correct!"
OK

"The correct promotion is:   1. f8(N)++  A double check!"
OK

BOARD 8/4kPQ1/4q3/32/6K1 WHITE
MOVELIST "f8Q"
"The double check with promotion to a Queen is murderous:  1. f8(Q)++  Note 
that all double checks are the result of line openings, or 'discoveries.'"
OK
  
BOARD 5rk1/5p2/6p1/8/2B5/8/2Q5/6K1 WHITE
MOVELIST "Qxg6"
"The King's position is often fatally weakened by a pin:   1. Qxg6+  This 
idea occurs frequently, because the Bishop is often developed on the a2-g8 
diagonal against a fianchettoed Bishop (Bishop developed at g7, here, but 
then traded off)."
OK

BOARD 7k/5Q1n/6P1/8/7q/16/6K1 WHITE
MOVELIST "g7"
"Just when everything seems protected, a Pawn slips in to mate:   1. g7++  
Pawns often mate when the enemy King is driven to the other side of the board."
OK

BOARD 24/6k1/4Q3/3B4/5B2/1K6 WHITE
MOVELIST "Qh4"
"It seems there are many ways to checkmate, but note that when the Queen 
checks adjacent to the enemy King, only two additional squares must be 
guarded -- two squares of the opposite color of the mating square:  1. Qh4++"
OK

BOARD 24/6k1/4Q3/3B4/5B2/1K6 WHITE
"The Queen check at f5 leaves h6 unguarded.  The Queen check at g6 leaves f4 
unguarded."
OK

BOARD 24/4k3/1Q6/4N3/4N3/1K6 WHITE
"Challenge #13:  What's the fastest way to checkmate?"
CHALLENGE Qe7 "That's right!"
OK

"The Black King seems to have many escapes, but a single move mates him in 
the open board:   1. Qe7++"
OK

END CHAPTER 
BOARD 64 WHITE
OK

//===================================================================
//Seventh chapter:  Level 6:  Basic Combinations
//===================================================================

BEGIN CHAPTER 6

BOARD 64 WHITE
//"Basic Combinations"
//OK

"Forks and skewers.  Double attacks.  Pseudo combinations."
OK

BOARD 24/3r1k2/8/5K2/4P3/8 WHITE
"The basic combinations all involve a double attack as the payoff.  They 
often start with a double threat."
OK

MOVE e4
"Here White is saved with a simple fork:  1. e4+.  In simplest terms, the 
King and the Rook can't both move at the same time."
OK

BOARD 24/1q3k2/16/4N2R/6K1 WHITE
MOVELIST "Nd4"
"Here White has the luxury of two forks.  The Rook double-attack is also 
called a 'skewer,' a name that's more vivid when a Bishop catches two enemy 
pieces on a diagonal:  1. Nd4+" 
OK

BOARD 24/1q3k2/16/4N2R/6K1 WHITE
MOVELIST "Rh5"
"or   1. Rh5+ winning the Queen."
OK

BOARD 6k1/1rn5/8/2K5/32 WHITE
MOVELIST "Kc6 Ra7 Kb6"
"The King is a fighting piece in the ending because it double-attacks well:  
1.Kc6 Ra7   2.Kb6."
OK

BOARD 7K/8/k1P5/7p/32 WHITE
"In this famous endgame study by Richard Reti, the White King can't get 'in 
the square' of the Black Pawn (formed by the diagonal d5-h1), but he can 
simultaneously threaten to get in the square and to support his own Pawn."
OK

MOVELIST "Kg7 h4 Kf6 h3 Ke6"
"1. Kg7 h4   2. Kf6...  First threat:  If the Pawn moves again, then 3. Ke6(7) 
forces the White Pawn to Queen."
OK

BOARD 16/k1P2K2/8/7p/24 BLACK
MOVELIST "Kb6 Ke5"
"2. ... Kb6   3. Ke5 ...  Second threat:   4. Kd6 again threatens to mobilize 
the Pawn.   3. ... Kxc6, and now:   4. Kf4 and White is in the square."
OK

BOARD 6k1/3p4/4pn2/8/2B1P3/2N5/8/6K1 BLACK
"Pawn forks are common in the opening as a way of exchanging center Pawns or 
reducing pressure."
OK

MOVELIST "Nxe4 Nxe4 d5"
"1. ... Nxe4   2. Nxe4 d5, forking the pieces and winning one back.  Note that 
White can also give up a piece at once (with Bxe6+).  It's a question of which 
Pawn White wants to win back."
OK

BOARD 6k1/16/q2N4/B2P4/8/1PP5/3QK3 WHITE
MOVELIST "c3"
"The Black Queen has just checked at a5, apparently forking both the Bishop 
at a4 and the Knight at d5."  
OK

"These are 'pseudo' forks, since:  1. c3 is a 'double defense' against the 
check and loss of the Bishop and..." 
OK

BOARD 6k1/16/q2N4/B2P4/8/1PP5/3QK3 WHITE
MOVELIST "Nc3"
"...1. Nc3! is a triple defense:  Blocking the check, removing the Knight 
from capture and guarding the Bishop."
OK

BOARD 6k1/16/2r5/2p5/2K1r3/16 WHITE
"Another pseudo fork:   1. Kd4 apparently forks the Rooks, but the defense 
is easy:   1. ... R (either) e5."
OK

BOARD 6k1/8/6n1/8/4B3/5r2/7K/8 BLACK
MOVELIST "Ne5"
"The White Bishop has apparently forked Knight and Rook.  Black could 
play   1. ... Ne5, defending the Rook,..."
OK

BOARD 6k1/8/6n1/8/4B3/5r2/7K/8 BLACK
MOVELIST "Rf6"
"...but even better, so as not to lose the exchange (Rook for minor piece), 
is   1. ... Rf6."
OK

BOARD 6k1/24/2r1n1P1/3P3K/16 BLACK
MOVELIST "Ng5+ Kh4 Nf3 Kg3"
"Some forks are very fragile indeed.  First, Black might try  1. ... Ng5+   
2. Kh4! Nf3+   3. Kg3 and the fork holds." 
OK

BOARD 6k1/24/2r1n1P1/3P3K/16 BLACK
MOVELIST "Nf2"
"But   1. ... Nf2+  in turn forks the King and Pawn,..."
OK

BOARD 6k1/24/2r1n1P1/3P3K/16 BLACK
MOVELIST "Rc3"
"...or   1. ... Rc3  pins and wins the poor Pawn."
OK

BOARD 8/k1q3r1/1p2N3/p7/8/Q7/6P1/6K1 BLACK
"Challenge #14:  Black's Queen and Rook are forked.  How does Black defend?"
CHALLENGE Qg3 "That is correct!"
OK

MOVELIST "Qxg3 Rxg3"
"The right idea is   1. ... Qg3! , which is both attack and defense:  if   
2. Qxg3 Rxg3  removes everything from attack."   
OK

BOARD 8/k1q3r1/1p2N3/p7/8/Q7/6P1/6K1 BLACK
MOVELIST "Rg3 Nxc7 Rxa3 Nb5"
"But not   1. ... Rg3  because of another White fork:   2. Nxc7 Rxa3   
3. Nb5+."
OK

BOARD 6K1/8/k1b1n2R/8/PP3P2/24 BLACK
"All good moves contain more than one element:  Immediate threats, immediate 
defenses, or threats of either."
OK

MOVELIST "Kb7 Rxe6 Bd5"
"Here, White threatens the half-pinned pieces or forks with   2. b5+.  Black 
defends by a move that unpins the Bishop and avoids the Pawn fork:  
1. ... Kb7   2. Rxe6 Bd5.  Now White is pinned!"
OK

BOARD 6K1/8/k1b1n2R/8/PP3P2/24 WHITE
"Note that   1. ... Bd5  at once loses to a further attack on the Knight:   
2. f5."
OK

BOARD 5k2/N3n3/6RP/3K4/8/5r2/16 WHITE
"Sharp tactics require experience, or a computer-like search of all 3-4 move 
variations!"
OK

MOVELIST "Ke4 Ra3 Rf6 Kg8 h7 Kh8 Rf8 Kh7 Rf7"
"Here White is forked, but holds on with short threats:  1. Ke4 Ra3
(1...Nxg6 draws)
2. Rf6+ Kg8 (NOT   2. Nb5 Ra4+)   3. h7+ Kh8 and wins because of Kh8.
4. Rf8+ forces him to take at h7 and lose the Knight to the fork  5. Rf7+."
OK

BOARD rn2k1nr/pp1qbppp/8/1p1Np3/3P4/5P2/PPP2P1P/R1BQKB1R WHITE
MOVELIST "Bxb5 Qxb5 Nc7"
"Put this all in a game situation:   1. Bxb5! happens all the time in 
positions like this:  The Black Queen is partially pinned and then forked 
after   1. ... Qxb5  2. Nc7+.  It's a 'Royal' check if Queen, Knight and 
Rook are all somewhere in the King's wheel."
OK

BOARD rnbqkbnr/ppp2ppp/8/3pP3/4P3/8/PPPP2PP/RNBQKBNR BLACK
MOVELIST "Qh4 Ke2 Qxe4"
"After two moves in the opening (King's Gambit), White is the victim of a 
typical fork:   3. ... Qh4+   4. Ke2 Qxe4+, or,"
OK

BOARD rnb1kbnr/ppp2ppp/8/3pP3/4P2q/8/PPPP2PP/RNBQKBNR WHITE
MOVELIST "g3 Qxe4 Ne2 Qxh1"
"if   4. g3 Qxe4+, Black wins the Rook."
OK

BOARD rnbqkbnr/ppp3pp/8/3pN3/3Pp3/8/PPP2PPP/RNBQKB1R WHITE
"Challenge #15:  A common opening situation:  How should White play?"
CHALLENGE Qh5 "That's right!"
OK

MOVELIST "g6 Nxg6 Nf6 Qe5"
"1. Qh5+ is the right start.  What about   1. ... g6?  You are right if you 
saw   2. Nxg6.  The h Pawn is pinned, so that   2. ... hxg6   3. Qxh8."
OK

"If   2. ... Nf6, the Queen can either retreat to h4, keeping the pin, or 
gain a move with   3. Qe5+, after which White wins the Rook."
OK

END CHAPTER   
BOARD 64 WHITE
OK

//===================================================================
//Eighth chapter:  Level 7:  Roots of Combinations
//===================================================================

BEGIN CHAPTER 7

//"Roots of Combinations"
BOARD 64 WHITE
//OK

"Pinned pieces.  Overworked pieces.  Restricted mobility."
OK

BOARD 3qk2r/4bppp/32/4QPPP/2B1R1K1 WHITE
MOVELIST "Bg5 f6"
"This is the schematic of a common opening pin, designed to keep
the Black King from castling.   1. Bg5 is met by f6, but White may
be able to play   1. Ba3, as here, winning the pinned piece."
OK

BOARD 1n2kb1r/3b1ppp/16/B7/8/5PPP/3R1RK1 WHITE
MOVELIST "Rd3 Ke7 Re1 Kd8 Rxd7 Nxd7 Rd1"
"Act on a pinned piece quickly!  Here White could try to 'double-up' with 
1. Rd3, threatening Rfd1.  But then Black escapes with Ke7.  1. Rfe1+ Kd8! 
also let Black get unpinned.  But:  1. Rxd7! Nxd7   2. Rd1 gets the piece."
OK

BOARD 3qk2r/3p1ppp/16/4n3/8/5PPP/3Q1RK1 WHITE
MOVELIST "Qe2 Qe7 Re1 d5 f3"
"Black has just taken at e4.  This schematic shows when a pin wins and when 
it doesn't in this typical opening:   1. Qe2?  Qe7 defends successfully.  
But:   2. Re1 d5   3. f3 wins the piece for a Pawn."
OK

BOARD 4k2r/3pqppp/8/4N3/5n2/8/5PPP/3QK2R WHITE
MOVELIST "O-O Qxe5 Re1"
"Sometimes the pinning piece gets pinned!   1. O-O Qxe5   2. Re1"
OK

BOARD r3k2r/pppqbppp/1n6/16/5Q2/PPP2PPP/RNB1R1K1 WHITE
"Challenge #16:  How does White take advantage of the pinned Bishop at e7?"
CHALLENGE Bg5 "That is correct!"
OK

MOVELIST "f6 Bf4"
"At most, White can disrupt the Kingside Pawns with:   1. Bg5 f6  2. Bf4 when 
White threatens two Queenside Pawns and can check on the a2-g8 diagonal when 
Black castles."
OK

BOARD r3k2r/pppqbppp/1n6/16/5Q2/PPP2PPP/RNB1R1K1 WHITE
MOVELIST "Qe2 O-O Qxe7 Rae8 Qxd7 Rxe1"
"The idea of keeping the Black King in the center with   1. Qe2 backfires 
after   1. ... O-O!   2. Qxe7 Rae8.  Now the Queen is pinned by the mate that 
would occur after   3. Qxd7 Rxe1++."
OK

BOARD r1b1k2r/ppq2ppp/2p5/4P3/8/2N5/PP3PPP/2RQ1RK1 WHITE
"Ideally, the Rooks are developed on the central files where they pose 
threats to the opposing Queen and King."
OK

"White's lead in development allows   1. Nb5!, since the c6 Pawn is pinned.   
1. ... Qxe5 is out, because of the common pin  2. Re1.  White's Knight will 
check at d6, keeping the King from castling."
OK

BOARD 5rk1/1b2qppp/8/1Ppp4/Q2P4/2N5/5PPP/5RK1 WHITE
MOVELIST "Qa3 Ra8 Na4 h6 Qxc5 Qxc5 Nc5"
"White pins and wins the c5 Pawn with  1. Qa3 Ra8   2. Na4 h6.   3. Qxc5 both 
attacks and defends.  On   3. ... Qxc5   4. Nxc5 (NOT dxc5)."
OK

BOARD 5rk1/5p2/6p1/7n/16/1B4P1/2K4R WHITE
MOVELIST "g4 Nf4 Rh8"
"A schematic of a typical Kingside pin:   1. g4 appears to win the Knight, 
because of   1. ... Nf4   2. Rh8++."  
OK

BOARD 5rk1/5p2/6p1/7n/16/1B4P1/2K4R WHITE
MOVELIST "g4 Ng7 Bf6"
"But the Knight can defend with  1. ... Ng7.  After  2. Bf6, the Knight is 
pinned along the diagonal and the Kingside is immobilized."
OK

BOARD 8/P7/8/5p2/4b2k/K1R4p/16 WHITE
"White wins a piece for the a Pawn with  1. Rc8, but loses the game after  
1. ... h2.  A pin forces the Queening of a Pawn."
OK

MOVELIST "Rc4 h2 Rxe4 fxe4 a8Q h1Q  Qh8"
"1. Rc4 h2   2. Rxe4+ fxe4   3. a8(Q) h1(Q)   4. Qh8+ wins."
OK

BOARD 4kn2/3p1p2/3P4/5P2/2P5/2n5/7K/7R WHITE
"The Rook is strong against two minor pieces when they have limited safe 
haven in the endgame:   1. Rc1.  If the Knight goes to the a or e file, 
Ra1 or Re1 wins it,  due to the direct pin on the e file and the threat 
of mate if the Knight moves off the a file."
OK

BOARD r4rk1/ppp1bppp/5n2/3P2B1/4p3/2N5/PPP2PPP/R4RK1 BLACK
"Challenge #17:  Does White win the e4 Pawn by pinning the defending Knight 
with  1. Bg5?  How would you respond for Black?"
CHALLENGE Nxd5 "That's right!"
OK

"The pin is illusory:  1. Bg5 Nxd5, attacking and defending at the same time."
OK

BOARD r4rk1/ppp1bppp/8/3n2B1/4p3/2N5/PPP2PPP/R4RK1 WHITE
MOVELIST "Nxd5 Bg5 Nc7 Rc8" 
"2. Nxd5 Bxg5   3. Nxc7 Rac8, where the Rook skewers the Knight and c2 Pawn." 
OK

BOARD r4rk1/ppp1bppp/8/3n2B1/4p3/2N5/PPP2PPP/R4RK1 WHITE
MOVELIST "Bxe7 Nxe7 Nxe4" 
"Best is   2. Bxe7 Nxe7   3. Nxe4, with an even game."
OK

BOARD 6k1/8/1n6/3p4/2r5/2NK4/16 WHITE
MOVELIST "Nxd5"
"Obviously, a pinned piece is immobilized.  Indirectly, an overworked piece 
is also hobbled:   1. Nxd5!  The Knight at b6 cannot defend both c4 and d5 in 
this schematic."
OK

BOARD 3r2k1/2q2ppp/2n5/3Q4/16/3R1PPP/6K1 WHITE
MOVELIST "Qxc6 Qxc6 Rxd8"
"The Black pieces seem to be working together, but the Queen is actually 
overworked:   1. Qxc6! and all of a sudden the twice-guarded Rook at d8 is 
unguarded after   1. ... Qxc6   2. Rxd8++."
OK

BOARD 3r2k1/2q2ppp/2n5/3Q4/16/3R1PPP/6K1 WHITE
MOVELIST "Qxc6 Rxd2 Qe8"
"Note that White must avoid the Black Queen after 1. ... Rxd2 and mate with   
2. Qe8++ or be mated!"
OK

BOARD 5bk1/2q2ppp/2pN1n2/6N1/7Q/8/5PPP/6K1 WHITE
MOVELIST "Ne8 Nxe8 Qxh7"
"The Knight at f6 is the King's best defender, but is overworked by the 
simple fork:  1. Ne8! Nxe8   2. Qxh7++ ...  As on other moves,   
2. Nxf6+ mates next move."
OK

BOARD 2r3k1/b2q1ppp/6b1/16/1Q2P3/5PPP/2R2BK1 WHITE
MOVELIST "Qa4"
"A weak back rank must be defended along its length.  Hence, the number of 
combinations based on pieces overworked in its defense:   1. Qa4!"
OK

BOARD 2r3k1/b2q1ppp/6b1/8/Q7/4P3/5PPP/2R2BK1 BLACK
MOVELIST "Bf5 Rxc8 Qxc8 Qxa7"
"White chooses this square carefully, since White now threatens  2. Qxa7 
(in response, for example, to 1. ... Qb7).  1. ... Bf5 allows   2. Rxc8+, 
followed by   3. Qxa7."
OK

BOARD 6k1/3q1ppp/8/Q3pb2/8/4P3/3rNPPP/5RK1 WHITE
"Challenge #18:  Black has an overworked piece.  Show how White can take 
advantage of it."
CHALLENGE Nd4 "That is correct!"
OK

"After  1. Nd4, the Black Queen must guard both the Bishop at f5 and the mate 
at d8.  The Rook must move to avoid   2. Qxd2."
OK

"The key move introduces the idea of 'cutting a line,' the file d7-d2.  
For, if  1. ... exd4,   2. Qxd2 wins the exchange (Knight for Rook)."
OK

BOARD 1r4k1/5p1p/6pQ/7N/8/1r1PP3/1q6/5R1K WHITE
MOVELIST "d4 gxh5 Rg1"
"Pawns are great for cutting lines, since they are expendable!  Here  1. d4! 
shuts off the Black Queen and threatens two mates.  1. ... gxh5 allows   
2. Rg1+ and mate next."
OK

BOARD 7k/1P3pp1/7p/7R/P7/8/6PK/1r6 WHITE
MOVELIST "Rb5"
"The Rook, Knight, or Bishop can cut a line along the back rank to help a 
Pawn to Queen (see Tutorial Level 4).  Here the Rook cuts a file with  
1. Rb5, a common theme in the endgame."
OK

BOARD 4k3/1p6/pP5p/P1PR4/r7/16/6K1 WHITE
MOVELIST "c6 bxc6 Rb5 axb5 b7"
"Here White cuts a 'potential' line:  1. c6 bxc6  2. Rb5! axb5  3. b7 and 
nothing can stop the Pawn from Queening."
OK

BOARD rn1q2r1/ppp4k/3p2p1/8/3Q4/1PB5/P4PPP/4R1K1 WHITE
"Challenge #19:  White controls the long diagonal.  But how does White take 
advantage of Black's stretched defenses?"
CHALLENGE Re8 "That's right!"
OK

MOVELIST "Qg5 Qh8 Rxh8 Rxh8"
"Both the Queen and the Rook are guarding e8, but are also trying to guard h4 
and g7, respectively."
OK

"Hence:  1. Re8! Qg5 (After  1. ... Qxe8  2. Qh4++ or  1. ... Rxe8  2. Qg7++)  
2. Qh8+! Rxh8   3. Rxh8 ++.  Note that   2. Rxg8 is too slow, in view of 
2. ... Qc1+ with mate to follow!"
OK

END CHAPTER 
BOARD 64 WHITE
OK

//===================================================================
//Ninth chapter:  Level 8:  Double Attacks
//===================================================================

BEGIN CHAPTER 8

BOARD 64 WHITE
//"Double Attacks"
//OK

"Discovered checks.  Forcing threats.  Destroying defenders."
OK

BOARD 3qk3/3p1p2/8/4N3/4n3/8/3P1P2/3QK3 WHITE
MOVELIST "Qe2 Nf6 Nc6"
"This schematic illustrates a familiar position in the Petroff Defense.  
Black has mistakenly played Nxe4:  1. Qe2 Nf6 (the worst idea)  2. Nc6+ 
winning the Queen."  
OK

BOARD 3qk3/3p1p2/8/4N3/4n3/8/3P1P2/3QK3 WHITE
MOVELIST "Qe2 f5 f3"
"But if Black tries to hold the Knight at e4, with  1. ... f5 (d5), White 
wins at least a Pawn with  2. f3."
OK

BOARD 1q3rk1/5p1p/6p1/8/4N3/2Q5/8/6K1 WHITE
MOVELIST "Nf6 Kh8 Nd7 Kg8 Nb8 
The 'hole' at f6 is an invitation to mayhem on the Black squares:  
1. Nf6+ Kh8  2. Nd7+ wins the Queen."
OK

BOARD 1q3r1k/5p1p/5Np1/16/2Q5/8/6K1 WHITE
MOVELIST "Ne8 f6" 
"Note that   2. Ne8+ guarding g7 does not lead to mate at g7, because Black 
simply interposes the Pawn   2. ... f6."
OK

BOARD 5rk1/6pp/8/6N1/8/7K/7Q/8 WHITE
MOVELIST "Qa2 Kh8 Nf7 Kg8 Nh6 Kh8 Qg8 Rxg8 Nf7"
"The best discovered check of all is a double check with a point:  Black 
cannot interpose on the checking line, or capture the checking pieces."
OK

"Here is the famous smothered mate, which occurs frequently in practice, 
mostly as a threat.  1. Qa2+ Kh8   2. Nf7+ Kg8   3. Nh6+ Kh8   4. Qg8+ Rxg8   
5. Nf7++."
OK

BOARD 7k/5p1B/7Q/32/6K1 WHITE
MOVELIST "Bg6 Kg8 Qh7 Kf8 Qxf7"
"When the battery fires, the leading piece can choose artfully.  Here is a 
typical mating sequence:  1. Bg6+ Kg8   2. Qh7+ Kf8   3. Qxf7++.  See the 
point of choosing g6 on the first move?"
OK

BOARD 3qk2r/5ppp/8/2b5/2Bp2b1/5N2/5PPP/3Q1RK1 WHITE        
"Sometimes the battery is directed against a minor piece trying to pin the 
leading piece in the battery.  (See Level 6 for examples of other 'pseudo' 
pins.)"
OK

MOVELIST "Bxf7 Kf7 Ne5 Kf8 Nxg4"
"1. Bxf7+! Kxf7   2. Ne5+, followed by   3. N(Q)xg4.  Note that   2. Ng5+ is 
a mistake, even with a White Bishop at c1 guarding that Knight.   2. ... Qxg5! 
and both Queens are in take (can be captured)."
OK

BOARD 5rk1/3rpppp/16/3p4/3B1N2/8/3Q2K1 WHITE
"Challenge #20:  How does White move immediately against the enemy King?"
CHALLENGE Bxh7 "That is correct!"
OK

MOVELIST "Kh7 Ng5 Kg8 Qh5"
"Bxh7+ is the start of many good mating attacks.  Nothing else is fast 
enough.  If:  1. ... Kxh7    2.Ng5+ Kg8,   3. Qh5 is the idea.  Black can 
defend with   2. ... Kg6."
OK

BOARD 3q1k2/r7/3p4/4p3/4P3/8/1PR5/1K5Q WHITE
MOVELIST "Rc8 Qxc8 Qh8 Ke7 Qxc8"
"The second stage in tactics is going beyond responding to setting up 
combinations.  Here White sets up a skewer:  1. Rc8! Qxc8   2. Qh8+ Ke7   
3. Qxc8."
OK

BOARD 1r1q2k1/1bpp1p1p/6p1/8/4N3/1Q6/3R1PPP/6K1 WHITE
"White seems to have run out of attacking ideas and is two Pawns down.  
A simple forking combination sets thing right:"
OK

MOVELIST "Rxd7 Qf8 Nf6 Kg7 Qc3"
"1. Rxd7! Qf8 (NOT 1. ... Qxd7, because of 2. Nf6+)  2. Nf6+ ... (NOT   
2. Ng5 Bd5!) and the weak back rank will cost White a move and the game.   
2. ... Kg7 (NOT   2. ... Kh8)   3. Qxf7! and White will mate at h7 
(See Level 5).  3. Qc3 ... "
OK

"The potential discovered checks give White a lasting initiative."
OK

END CHAPTER   
BOARD 64 WHITE
OK

//===================================================================
//Tenth chapter:  Level 9:  Sacrifices
//===================================================================

BEGIN CHAPTER 9

BOARD 64 WHITE
//"Sacrifices"
//OK

"Queen sacrifices.  The exchange sacrifice.  Pawns, minor pieces."
OK

BOARD 8/1bq2pkp/5pp1/16/Q3B2K/2r5/4R3 WHITE
MOVELIST "Qf8 Kxf8 Bh6 Kg8 Re8"
"Black's attack appears unanswerable, yet a Queen sacrifice sets up a 
standard back-rank mate:   1. Qf8+! Kxf8   2. Bh6+ Kg8   3. Re8++.  It 
can't be said enough:  Watch out for a weak back-rank!"
OK

BOARD 2k2brr/1ppbq3/2np4/1B6/Q7/4B3/6P1/1R3RK1 WHITE
MOVELIST "Qa8 Nb8 Qxb7 Kxb7 Bxd7 Ka6 Bc8 Ka5 Bd2 Ka4 Rb4 Ka3 Ra1"
"The Queenside is notorious for spectacular attacks on a castled King.  
This is one of the prettiest:  The idea is to set up a discovered check.  
1. Qa8+ Nb8   2. Qxb7+! Kxb7   3. Bxd7+ Ka6   4. Bc8+ Ka5   5. Bd2+ Ka4   
6. Rb4+ and   7. Ra1++"
OK

BOARD 1r2k1r1/pbppnp1p/1bn2P2/8/Q7/B1PB1q2/P4PPP/3RR1K1 WHITE
"One of the most famous positions in chess history is Anderssen's 'immortal' 
game against Dufresne, 1852.  Black threatens mate, so every move must be a 
check."
OK

MOVELIST "Rxe7 Nxe7 Qxd7 Kxd7 Bf5 Ke8 Bd7 Kd8 Bxe7"
"1. Rxe7+! Nxe7   2. Qxd7+! Kxd7   3. Bf5+ Ke8   4. Bd7+ Kd8(f8)   
5. Bxe7++.  Note also the interesting mate if   3. ... Kc6   4. Bd7++."
OK

BOARD r2qkbnr/ppp2p1p/3p2p1/4n3/2B1P1b1/2N2N2/PPPP1PPP/R1BQK2R WHITE
"Challenge #21:  The Knight at f3 is pinned and the Bishop at c4 attacked.  
What's White's best move?"
CHALLENGE Nxe5 "That's right!"
OK

MOVELIST "Bxd1 Bxf7 Ke7 Nd5"
"White wins a piece or checkmates with:  1. Nxe5! Bxd1   2. Bxf7+ Ke7   
3. Nd5++.  Legal played this first in the 18th century."
OK

BOARD 2kr3r/pp5p/2p2p2/3n2pb/1P2N3/P7/5PPP/2BRR1K1 WHITE
MOVELIST "Rxd5 cxd5 Nxf6 Bg6 Bxg5"
"A well-posted Knight, such as the one at d5, is often worth a Rook.  White 
takes the wheels off Black's position with   1. Rxd5! cxd5  2. Nxf6 Bg6   
3. Bxg5.  Note the winning fork after   1. ... Rxd5   2. Nxf6."
OK

BOARD 2rq1rk1/1p2ppbp/p5p1/3Pp2n/5P1Q/2N2N2/PPP3P1/2KR3R BLACK
"The exchange sacrifice (Rook for minor piece) often occurs at h5 against a 
Kingside castled King, or at c3 against a Queenside castled King."
OK

MOVELIST "Rxc3 bxc3 Qa5 Kb2 e4"
"Here Black comes first:   1. ... Rxc3   2. bxc3 Qa5.  Note that there is no 
gain of material:  Simply a weakening of the King position and the frightful 
threat of   3. ...  e4 after   3. Kb2."
OK

BOARD r2q1rk1/1p1n1p1p/p2p2p1/2pP4/2Pb4/2N5/PP2Q1PP/R1BR3K WHITE
MOVELIST "Rxd4 cxd4 Ne4 Ne5 Bh6 Re8 Rf1"
"General positional considerations, such as control of dark squares or better 
Knight placement, often cry out for the exchange sacrifice:  1. Rxd4! cxd4   
2. Ne4  with a complicated game:  If  2. ... Ne5, then  3. Bh6 and  4. Rf1."
OK

BOARD rn3k1r/p4ppp/3p4/1p6/1n1P4/8/PPP2PPP/R1B1KB1R WHITE
"The threat to win the exchange with a fork by the Black Knight at b4 is a 
common theme in the early endgame -- especially with Queens off the board."
OK

MOVELIST "Bf4 Nxc2 Kd2 Nxa1 Bxd6 Kg8 Bxb5"
"Here White can try for more than pedestrian defense   (1. Kd1):  
1. Bf4?! Nxc2+ (White gains a move if   1. ... Ke7   2. Kd2.)  2. Kd2 Nxa1   
3. Bxd6+ Kg8   4. Bxb5 regaining the piece with a great lead in development."
OK

BOARD r4rk1/ppqn1p2/2p2p1p/4n2Q/2P5/1P4P1/PB4BP/3R1RK1 WHITE
"Challenge #22:  White has the two Bishops.  Does White have a better move 
than   1. Qxh6, regaining a Pawn and threatening   2. Rf5?"
CHALLENGE Rxd7 "That is correct!"
OK

MOVELIST "Nxd7 Rxf6 Nxf6 Bxf6 Qd7 Qxh6"
"The forceful way to end matters is:  1. Rxd7 Nxd7  2. Rxf6!  The second 
exchange sacrifice denudes the King:  2. ... Nxf6   3. Bxf6 Qd7   4. Qxh6 
with mate to follow."
OK

BOARD r1b1k2r/1p1nbppp/pq1ppn2/6B1/2BNP3/2N5/PPPQ1PPP/R3K2R WHITE
MOVELIST "O-O Qxb2 Rab1 Qa3"
"The b and g Pawns are the most vulnerable in the opening and are commonly 
sacrificed to gain time."
OK

"Note that, typically, a Knight must be available at c3, c6, f3, or f6 to 
support a Rook at b1, b8, g1, g8.  1. O-O Qxb2  2. Rab1 Qa3 with a lead in 
development."
OK

BOARD rnbqk1nr/ppp2ppp/4p3/3p4/1b1PP3/2N5/PPP2PPP/R1BQKBNR WHITE
MOVELIST "Qg4 Nf6 Qxg7 Rg8 Qh6 Rg6 Qh4 Nxe4"
"A standard French Defense.  Is g7 weak because the Black Bishop has moved?  
1. Qg4 Nf6!   2. Qxg7 Rg8   3. Qh6 Rg6   4. Qh4 Nxe4, with a good game for 
Black."
OK

BOARD 3qkb2/3npp2/3p4/4P3/8/3B1N2/8/3QK3 WHITE
MOVELIST "e6 fxe6 Ng5"
"Here is a schematic depiction of a frequent Pawn sacrifice on rank 6 or 3:  
1. e6 fxe6  2. Ng5"
OK

"The idea in such positions is to delay the development of the Bishop and 
establish weaknesses at e6 and f7."
OK

BOARD 5bk1/8/3rpp2/8/4P3/2N2P2/8/5RK1 WHITE
MOVELIST "e5 fxe5 Ne4"
"This schematic illustrates a Pawn sacrifice to gain a strong position for a 
minor piece:  1. e5! fxe5  2. Ne4 and the Knight is strongly posted against 
the Black Bishop."
OK

BOARD 8/7R/2r5/8/P3n3/8/3nk1PP/R5K1 BLACK
MOVELIST "Nf3 gxf3 Rg6 Kh1 Nf2"
"Minor piece sacrifices (Knights and Bishops) open doors to mating attacks.  
Even if a mate is prevented, the attacker can often recover 2-3 Pawns because 
of the exposed position of the King."
OK

"Here the attack comes out of the blue; a famous Karpov mate in three:  
1. Nf3+! gxf3   2. Rg6+ Kh1   3. Nf2++"
OK

BOARD 6k1/7p/4p3/1p1n1pp1/8/7K/Pr5P/3Q4 BLACK
MOVELIST "Rg2 Kxg2 Ne3 Kg1 Nxd1"
"A quiet rook sacrifice threatens mate in a most unusual way and a deadly 
fork shows that it's really no sacrifice at all:  1. ... Rg2!   
2. Kxg2  Ne3+   3. ... Nxd1"
OK

BOARD r5rk/5Q1p/p4P2/qp1p4/3B4/1P5P/P4P2/R3b2K WHITE
"When a piece merely has to clear a line or a square to create a strong 
threat, it becomes a 'desperado' -- one who cares nothing for its life, 
only for choosing the right square."
OK

MOVELIST "Qe8 Raxe8 f7 Rg7 fxe8Q"
"1. Qe8! Raxe8   2. f7+ Rg7   3. fxe8 (Q)++.  The Queen move prevents Raf8, 
which is why  1. Qf8 is wrong."
OK

BOARD 6k1/40/4B3/2Q2nK1 WHITE
"Now start from the elements of a famous combination.  See how a World 
Champion visualizes a winning sequence of moves:  1. ... Ng3 extricates the 
Knight from danger and threatens the fork   2. ... Nxe7+."
OK

BOARD 4r1k1/4qppp/3P4/16/4P1P1/4BP2/2Q2nK1 BLACK
MOVELIST "Nxg3"
"As the position builds up in reverse slow motion, notice that even though 
the Black Queen is in take   1. ... Nxg3! is an 'in between' move 
(zwischenzug) that says, 'Pardon me, but I'll take a Pawn first instead of 
dealing with my Queen.'"
OK

BOARD 1rb1r1k1/p1p1qppp/2pb4/2P5/8/4P1P1/PB2BP1n/R1QN1RK1 BLACK
MOVELIST "Nxf1 cxd6 Nxg3"
"Two moves further back, this is how Karpov viewed his game against Timman.  
Black can play:  1. ... Nxf1! c5xd6  2. Nxg3!"
OK

BOARD 1rb1r1k1/p1p1qppp/2pb4/2P5/8/4P1P1/PB2BP1n/R1QN1RK1 BLACK
MOVELIST "Bxc5 Kh2"
"Black could, of course, play   1. ... Bxc5.  But then the pin is off the 
g3 Pawn and White simply takes the Knight at h2.  The zwischenzug is a 
suspension of reality that makes combinations possible."
OK

BOARD 1rb1r1k1/p1p1qppp/2pb4/8/2P3n1/4P1P1/PB2BP1P/R1QN1RK1 BLACK
MOVELIST "Nxh2 Kxh2 Qh4 Kg1 Bxg3 fxg3 Qxg3 Kh1 Re6"
"Here is the position after White's 15th move in this Montreal, 1979 game 
(see Classic Game 131).  Black had to visualize the previous position to 
play the piece sacrifice:  1. ... Nxh2!   2. Kxh2."
OK

"White makes a zwischenzug, instead of the prosaic   2. Kxh2 Qh4+   
3. Kg1 Bxg3!   4. fxg3 Qxg3+   5. Kh1 Re6, when White will soon be mated."
OK

BOARD 1rb1r1k1/p1p1qppp/2pb4/8/2P3n1/4P1P1/PB2BP1P/R1QN1RK1 BLACK
MOVELIST "Nxh2 c5 Nxf1 cxd6 Nxg3"
"The Karpov - Timman game went as follows:  1. ... Nxh2   2. c5 Nxf1   
3. cxd6 Nxg3"
OK

BOARD r1b2rk1/pp1p1pbp/6p1/8/2PBq3/8/PP2BPPP/R2QK2R WHITE
MOVELIST "Bxg7 Qxg2 Qd4 Qxh1 Kd2 Qxa1 Qf6 d6 Bh6"
"White is ahead in development, but appears to be about to lose a 
Pawn -- the usual 'poisoned' Pawn at g2.  1. Bxg7 Qxg2?  Black sees only  
2. Bf3 Re8+, remaining a Pawn up.  2. Qd4! Qxh1+  3. Kd2 Qxa1  4. Qf6!"
OK

"Now there's nothing to do about  5. Bh6 and mate to follow."
OK

"A famous 'double Rook' sacrifice by the former Women's World Champion, 
Nona Gaprindashvili."
OK

BOARD r4rk1/1b2bppp/ppq1p3/2ppB2n/5P2/1P1BP3/P1PPQ1PP/R4RK1 WHITE
"The 'double Bishop' sacrifice is always possible when the King's natural 
defender, the Knight, is lured away and a Rook can readily move to rank 3."
OK

MOVELIST "Bxh7 Kxh7 Qxh5 Kg8 Bxg7 Kxg7 Qg4 Kh7 Rf3" 
"1. Bxh7+ ... (Instead of 1. Qxh5 g6) and Black can organize a defense.  1. 
... Kxh7   2. Qxh5+ Kg8   3. Bxg7! Kxg7   4. Qg4+ Kh7   5. Rf3, with mate to 
follow.  This was Emanual Lasker's first memorable victory, Amsterdam, 1889."
OK

BOARD 8/p3q1kp/1p2Pnp1/3pQ3/2pP4/1nP3N1/1B4PP/6K1 WHITE
"Challenge #23:  White has an advanced Pawn.  How does White dislodge the 
Black Queen?"
CHALLENGE Ba3 "That is correct!"
OK

MOVELIST "Qxa3"
"1. Ba3! Qxa3  White's pieces have few other moves!"
OK

BOARD 8/p5kp/1p2Pnp1/3pQ3/2pP4/qnP3N1/6PP/6K1 WHITE
"Challenge #24:  How does White move the Pawn to the queening square?"
CHALLENGE Nh5 "That is correct!"
OK

MOVELIST "gxh5 Qg5 Kf8 Qxf6 Kg8 e7" 
"If you tried  2. Qc7+, you would be rewarded with a mate after  
2. ... Kf1.  But Black escapes with   2. ... Kh6.  Also,   2. e7 is met 
immediately by  2. ... Kf7.  So:  2. Nh5+! gxh5  3. Qg5+ Kf8  4. Qxf6+ Kg8  
5. e7."
OK

"After several checks, the White King was safe and Black, Capablanca, 
resigned to Botwinnik (see Classic Game 82)."
OK

END CHAPTER  
BOARD 64 WHITE
OK

//===================================================================
//Eleventh chapter: Level 10:  Strategy 
//===================================================================

BEGIN CHAPTER 10

//"Strategy"
BOARD 64 WHITE
//OK

BOARD rnbqkbnr/pppppppp/32/PPPPPPPP/RNBQKBNR WHITE
"Pawns and Strong Points.  Development and Control.  Transitions."
OK

MOVE e4 
MOVE e5
"Chess strategy begins with the initial moves of the game.  Here both sides 
play to open the lines for their Bishops and Queens.  By playing the double 
move instead of e3 or e6, they keep the potential line of the Queens' Bishops 
also open."
OK

MOVE Nf3
MOVE Nc6
"Since the Knights have fewer options than Bishops, it's generally better to 
develop them first.  In the opening or middle game, the first rule is to keep 
all possible options open!"
OK

MOVELIST "Nxe5 Qe7 Nf3 Qxe4 Be2"
"2. ... f6 would have been poor because of  3. Nxe5 Qe7 (NOT 3. ...  fxe5  
4. Qh5+ and White soon wins material or checkmates)  4. Nf3 Qxe4+  5. Be2 
and White has a big lead in development."
OK

"2. ... Bd6 would also have restricted Black's development, blocking the 
d Pawn and impeding the Queen's Bishop."
OK

BOARD r1bqkbnr/pppp1ppp/2n5/4p3/4P3/5N2/PPPP1PPP/RNBQKB1R WHITE
MOVELIST "Bb5 a6"
"White threatens to undermine the Knight's defense of the e Pawn.  However, 
it is immune as long as White's e Pawn is also vulnerable.  For example:  
3. Bxc6 dxc6  4. Nxe5 Qe7, regaining the Pawn."
OK

BOARD r1bqkbnr/1ppp1ppp/p1n5/1B2p3/4P3/5N2/PPPP1PPP/RNBQK2R WHITE
MOVELIST "Ba4 Nf6"
"By continuing to develop normally, Black keeps the balance in the center 
(the squares d4, d5, e4, e5)."
OK

"A move like  3. ... Qf6 is premature, because the Queen can do little 
damage this early in the game and is easily harried by minor pieces:  
4. Nc3, threatening  5. Nd5." 
OK

BOARD r1bqkb1r/1ppp1ppp/p1n2n2/4p3/B3P3/5N2/PPPP1PPP/RNBQK2R WHITE
MOVE 0-0 
"White's e4 Pawn is 'protected' by the rapid mobilization of the Rook, 
in castling.  If:   5. ... Nxe4   6. Re1 f5   7. d3 ... and Black's e5 Pawn 
will fall."  
OK

MOVELIST "d6 d4 Bg4"
"White usually plays  6. d4 here, because the Knight will be pinned on the e 
file if  6. ... exd4."
OK

BOARD r2qkb1r/1pp2ppp/p1np1n2/4p3/B2PP1b1/5N2/PPP2PPP/RNBQ1RK1 WHITE
"Challenge #25:  How does White get a better Pawn position?"
CHALLENGE Bxc6 "That's right!"
OK

"The idea is  7. Bxc6+."
OK

MOVELIST "bxc6 dxe5 Bxf3 Qxf3 dxe5 Rd1 Bd6 Bg5 Rb8"
"7. ... bxc6.   8. dxe5.  To avoid losing a Pawn, Black must now play   
8. ... Bxf3  9. Qxf3  dxe5.  Black's Queenside Pawns are now weak (the a 
Pawn isolated and the c Pawns doubled).  White now mobilizes rapidly:  
10. Rd1 Bd6  11. Bg5 Rb8"
OK

BOARD 1r1qk2r/2p2ppp/p1pb1n2/4p1B1/4P3/5Q2/PPP2PPP/RN1R2K1 WHITE
"Challenge #26:  White controls more space and has a better Pawn structure.  
How should White guard b2?"
CHALLENGE Nd2 "That is correct!"
OK

"12. Nd2.  If  12. ... Rxb2, then  13. Nc4 Rxc2  14. Qd3 would win the 
exchange.  The Rook is badly placed after  13. ... Rb5  14. a4 Rc5.  
15. Qd3, followed by  16. Be3."
OK

MOVELIST "O-O Nc4 Re8"
"Black chooses to get the King to safety rather than take the Pawn at b2.  
But now the d6 square is seriously threatened:  12. ... O-O  13. Nc4 Re8"
OK

"The most difficult challenge of chess is to work out a plan of action in 
a fairly level position."
OK

"Is the Black King position weak enough that  14. Rd3, followed by  15. Qf5 
and  16. Rg3 might succeed?  Or should White go after the weak a Pawn with  
14. Qc3 and  15. Qa5?"
OK

BOARD 1r1qr1k1/2p2ppp/p1pb1n2/4p1B1/2N1P3/5Q2/PPP2PPP/R2R2K1 WHITE
MOVE Rd3
"14. Rd3 ... Here is a good example of keeping options open.  This move 
threatens to double the Rooks on the d file.  14. Qc3 shows that the Knight 
is not always pinned:  14. Nxe4!"
OK

"Challenge #27:  How does Black defend against  15. Rad1?"
CHALLENGE Re6 "That's right!"
OK

"Now Black threatens to get free, finally, with  15. ... h6."
OK

"Rapid development, open lines and early castling are often rewarded in 
bright combinations."
OK

BOARD 3rkb1r/p2nqppp/5n2/1B2p1B1/4P3/1Q6/PPP2PPP/2KR3R WHITE
"Here, White has sacrificed a piece to trap the Black King in the center, 
in a state of cramped but apparent solidity."
OK

MOVELIST "Rxd7 Rxd7 Rd1 Qe6 Bxd7 Nxd7 Qb8 Nxb8 Rd8"
"(For the full game, see Classic Game 4.)  White first reduces the 
defenders:  1. Rxd7! Rxd7   2. Rd1 Qe6  3. Bxd7+ Nxd7  4. Qb8+! Nxb8  
5. Rd8++.  This brief instruction ends with an immortal game of Paul Morphy."
OK

END CHAPTER
