Consider the following diagram:
4k3/3b4/6p1/1p6/pP3P2/P7/8/4K3 b
Black is Pawnitized
Here, despite his extra bishop, Black cannot win this ending. This is because all of White's pawns are on opposite-colored squares than the color of the bishop. Here, we say that White has "pawnitized" Black (rendered his bishop useless). This terminology is due to siggemannen.
Therefore, if your opponent has an extra bishop, you still have hope to draw. Consider:
8/p7/2p2p2/5n2/2k2P2/2P5/P7/3KBN2 b
Black to Move and Draw
Here, Black's first priority is exchanging knights: 1. ... Ne3+ 2. Nxe3. Now, Black has two pawns sitting on dark squares that must be pushed to light squares. Which one should be pushed first? 2. ... f5. Of course. Otherwise, White would play f5 himself, fixing the pawn on f6, where it will get exchanged later for White's bishop and White would win. Now: 3. Bf2 a6 draw.
8/8/p1p2p2/8/2k2P2/2P5/P4B2/3K4 w
Drawn
Now, Black will just leave the pawns where they are and shuffle his king around. White can't make any progress.
Next, consider:
8/p7/1kp2p2/8/8/2P5/P4P2/3KB3 w
White to Move and Win
Here, White must act quickly before Black gets his pawns to light squares. White has only one winning move: 1. f4! A double-threat. White threatens both 2. f5 and 2. Bf2+. Black has no defense. If 1. ... f5, then 2. Bf2+ Kb5 3. Bxa7! [1-0], and if 1. ... a6, then 2. f5 Kc5 3. Bh4 Kd6 4. Bxf6 [1-0].
One of the first times I was acutely aware of pawnitization was while analyzing my favorite opening: 1. e3 e6 2. Nf3 f6 3. Nd4 c6 4. Nb5 cxb5 5. Qh5+ g6 6. Qb5 Nc6 7. Qb6! Kf7 8. Qc7 Bb4 9. c3 Qf7.
r1b2qnr/ppQp1k1p/2n1ppp1/8/1b6/2P1P3/PP1P1PPP/RNB1KB1R w
White to Move
The tactics executed to arrive at this position were discussed in the chapter "Queen Tactics". White has performed a "hook" and Black has executed tipau's defense to the hook. I have done a lot of analysis from this position and for a short time, I used to think that White's best line was: 10. Bc4 Bxc3 11. Nc3 Ne7 12. Nd5 Nxd5 13. Qd8 Qxd8 14. b4 Rhc8! 15. Bb2 f5! 16. Bc3.
r1r5/pp1p1k1p/4p1p1/5p2/1P6/2B1P3/P2P1PPP/R3K2R b
Black to Move
However, White is just about pawnitized! All Black has to do is move his a-pawn to a light square or make sure that it cannot be taken by White's bishop. The position is drawn. Note how Black's last two moves were designed to pawnitize White. After a while, I found the improvement 13. b4! instead of 13. Qd8 :
r1b2q1r/ppQp1k1p/4ppp1/8/1P6/4P3/P2P1PPP/R1B1K2R b
Black to Move
Here, White will get his bishop to b2 before trading queens, thus avoiding pawnitization. Black is practically in zugzwang here (no useful moves). For example, if 13. ... Qh6?? then 14. Qd6 [1-0] wins. White has plenty of time to put his bishop on b2 and move his queen to d8 later.
Next, we shall discuss defenses to pawnitization. Even when you have been seemingly pawnitized, there may occasionally be hidden tactics to unpawnitize yourself. Consider:
4k3/3p1p2/6p1/2P3B1/4P3/8/5P2/4K3 w
White to Move and Win
Sordid vs. Rekursiv
Here, White is pawnitized. But he can unpawnitize himself with 1. Be7! (Too bad the computer Sordid didn't understand pawnitization; he played 1. f4?? instead and went on to draw.) Now, my king is stalemated and any pawn move loses. If 1. ... g5 then 2. Bxg5 [1-0]. If 1. ... f6 then 2. Bxf6 [1-0]. If 1. ... f5 then 2. e5 [1-0] and White would force a promotion. If 1. ... d6 then 2. Bxd6 (or 2. c6) [1-0]. Finally, if 1. ... d5, then 2. c6 [1-0].
Fascinated by this, I tried to create more interesting positions where pawnitization can be defeated. Consider:
8/8/8/8/5p2/7K/5kP1/4b3 b
Black to Move and Win
The idea here is that White cannot step on any of the 8 squares adjoining f3. If he does, Black will advance his pawn and White cannot take it. So, Black can use his king and bishop to force White to an undesirable square or to advance his pawn like this: 1. ... Kg1 2. Kh2 Bg3 3. Kh3 (3. Kh1 Bh2 4. g3 f3 [0-1]) 3. ... Kh2 4. Kg4 f3 [0-1].
8/8/8/8/6K1/5pb1/6Pk/8 w
White is Lost
Now, White cannot take the pawn and Black's next move is f2. So, White is lost. This same basic position arose in a game HyperMagnus vs. Rekursiv, which played to this position:
8/2K1P3/3P4/P1Pp1P2/p1p4B/1p6/6p1/3k4 w
White to Move
White has to act quick to have any chance at all of getting Black into zugzwang as in the previous position. He does: 1. d4 exd3 e.p. 2. e4 fxe4 3. c5.
8/2K5/8/P1P5/p4P1B/1p6/6p1/3k4 b
Black to Move
Black is forbidden to move his king to any square within the red outlines lest White advance a pawn safely. But Black has enough room to avoid these danger squares. In fact, he could move his king endlessly within the four squares e8-e7-f7-f8. White cannot use his king and bishop to evacuate him from all four of those squares. However, the point of this example is to show that Black must be aware of this, and he must not take the position too lightly. In the actual game, play continued: 3. ... Kf8 4. Bd8 Kf7 5. Be7 Ke8 6. Ke3 Kf7 7. Kd4 Ke8 8. Ke5 Kf7 9. Ke6 Ke8 10. Kd7 Kd8??
8/8/8/P1P5/p4P2/1p6/2KB2p1/4k3 w
White to Move and Win
Black gives up his safe e8-e7-f7-f8 squares for no reason! Now he is lost. White will force him into the danger squares: 11. Ke8! Kc8 12. Kd8 Kb8 13. Bd6+ Ka7 (13. ... Kc8 14. Bb8! [1-0]) 14. Bc7 Ka6 (14. ... Ka8 15. Bb8 [1-0]) 15. Bb6 g5 16. fxg5 Kb5 17. c6!
8/8/8/P7/p5k1/5PB1/6p1/4K3 b
White Wins
You know the rest.
I'll end this chapter with a few more simple examples of defeating pawnitization. Consider:
2k5/8/2b5/8/1p1p4/8/1P1P4/2K5 b
Black to Move and Win
Black is pawnitized and he must act quickly before the White king escapes to fresh air. He wins like this: 1. ... Ba4! 2. Kb1 Bc2+ 3. Ka1 Bb1.
2k5/8/8/8/1p1p4/8/1P1P4/Kb6 w
Black Wins
Now White is forced to move a pawn to a light square, and so Black wins. In fact, Black can win without ever queening in this position! He proceeds like this: 4. d3 Kd8 5. b3 Ba2! 6. Kb2 Bxb3##
Next consider:
2k4b/1ppp4/7p/3P3P/2P5/1P6/8/2K5 b
Black to Move and Win
Black is pawnitized, but if White leaves his pawns where they are, then Black's plan is to trade his b-pawn for White's c-pawn and his c-pawn for White's d-pawn. Then he will have a passed d-pawn that will win. Black begins: 1. ... Bb2+ 2. Kd1 Ba3. While, not necessary, having the bishop on a3 watches over the White pawns and can snap them up if any advances, thus unpawnitizing himself. Play continues: 3. Ke2 c6 4. Kf3 cxd5 5. Kg4 b5 6. Kf5 bxc4 [0-1].
Finally, we end the chapter with this amusing position:
5b1k/p7/8/8/8/2p1p1p1/P1P1P1P1/2K5 b
Black to Move and Win
Here, Black begins with: 1. ... Ba3+ and now White has two ways to die. First: 2. Kb1 a5 3. Ka1 a4 4. Kb1 Bb2 5. a3 Kg7 6. Ka2 Bxa3##. Second: 2. Kd1 a5 3. Ke1 a4 4. Kd1 Bc1 5. Ke1 Bd2+ 6. Kf1 Be1 7. Kg1 Bf2+ 8. Kh1 Kh7 9. a3 Be1 10. Kg1 Bd2 11. Kf1 Bc1 12. Ke1 Bxa3 13. Kd1 a3 14. Kc1 a2 15. Kd1 a1=R#.