Sunday, June 22, 2014

Winter Melon

When I'm not playing chess, sometimes I play Plants versus Zombies. One of my favorite weapons to plant is the Winter Melon which not only causes splash damage, but it also slows down the zombies over a 3x3 area.

Recently, I almost gave away my copy of Chernev's Practical Chess Openings. But after my last endgame debacle, I went looking for a reference on rook versus two connected pawns and found it in Chernev's book. Perusing the beginning pages, I ran across some pawn endings that were far from trivial. In each of these three endgame studies, it is helpful to remember that the attacking king can be used like the Winter Melon to slow down the enemy pawn.

Practical Chess Endings #23
Grigoriev 1928

White to play and win

It should be clear after a little calculation that a pure pawn race leads to a draw. Even though White's pawn can queen with check, Black's pawn first reaches b3 and gains a tempo because of the check on White's king. e.g. 1.g4? b5 2.g5 b4 3.g6 b3+ 4.Kd2 b2 5.g7 b1Q 6.g8Q+ 7.Qb3=. Because of this, White embarks on a short walk with his king to c4, forcing Black to mirror the same short walk to a4. When Black's pawn checks the White king during its advance, White moves the king back toward c2 via d3. This forces Black to move his king back to a2. White then queens with check and wins. In the drawing line above, Black moves his king zero times to White's one time. In the following winning line, White and Black each move their kings four times before White queens with check.1.Kc3! Ka3 2.Kc4! Ka4 3.g4! b5+ 4.Kd3! b4 5.g5! b3 6.g6! b2 7.Kc2! Ka3 8.g7! Ka2 9.g8Q+! Ka3 10.Qb3#

Practical Chess Endings #24
Duras 1905

White to play and win

I have previously generalized that it is dangerous to step on a square that allows the opponent to queen with check, but in this study, that's the only move that wins. If 1.Kc4?, then Black steps in front of his own pawn 1...Kg6 or 1...Kg5 and can draw by hightailing it to b8, preventing White from queening. The key idea is to invest time moving the White king from c5 to f2. This forces Black to move his king to h2 where it will be checked by the new White queen. 1.Kc5! g5 2.b4! g4 3.Kd4! g3 4.Ke3! Kg5 {slowed} 5.b5! Kg4 {slowed} 6.b6! g2 7.Kf2! Kh3 {slowed} 8.b7! Kh2 {forced onto a queen-with-check square} 9.b8Q+ Kh3 10.Qg3#

Practical Chess Endings #25
Mandler 1938

White to play and win

Notice that White has a bishop pawn this time instead of a knight pawn in the two other studies. Again, one idea I have in endgames is that you should try to gobble your opponent's pawns as fast as you can. Here 1.Kxb7? only draws because Black can run down White's pawn beginning with 1...Kb3! 2.f4 (2.Kc6 Kc4! 3.f4 Kd4!=) 2...Kc4! 3.f5 Kd5!=. Of course, a pure pawn race only draws. 1.f4? b5 2.f5 b4 3.f6 b3 4.f7 b2 5.f8Q b1Q=. Instead, White wins by doing triple duty with his king: 1.blocking the Black king from chasing White's pawn along the a2-f7 diagonal, 2.slowing down Black's pawn advance later moves, and 3.helping to threaten mate after the pawns queen. 1.Kd6! Ka3 {slowed} (1...b5 2.Kc5 Kb3 3.Kxb5 Kc3 4.Kc5 {and White will preserve his pawn for the win.}) 2.Kc5! Ka4 {slowed} 3.f4! b5 4.f5 b4 5.Kc4 b3 6.Kc3! Ka3 {forced onto a queen-with-check square} 7.f6 b2 8.f7 b1Q 9.f8Q+ Ka4 10.Qa8+! Kb5 11.Qb8+ Kc5 12.Qxb1.

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