7th Winterthur 
Pawn endings from previous Chess Weeks: Solutions
Position 1:
Michèle Britschgi-Zwimpfer — Roman Freuler
Winterthur Chess Week 2006
Black to move wins
Solution:
The white king safely stops the h-pawn and hinders black to approach the pawn f3 via h4. Hence the only plan for black to win is to bring his king to e3.
While doing that, he has to be careful not to lose his important pawn on f4. White has access to this pawn via g4 or g5 and it is an obvious idea to control one of these squares with the pawn h7. But which square?
A) In the game, black decided to protect the g4 square by 65... h5? But after 66. Kg2 Kf5 67. Kh3 Kg5 68. Kg2 Kh4 69. Kh2 Kg5 70. Kh3 Kg6 71. Kh4 Kh6 72. Kh3 Kg5 73. Kg2 Kf6 no progress was possible. The critical position arises after the moves 74. Kh3 Ke5 75. Kh4 Kd4 76. Kh5: Kd3? (This "winning attempt" leads to disaster, 76...Ke5 would still be a draw.):
The squares highlighted in red are so-called "mined squares"; the first to move on these will be disadvantaged. In the position above the side to move will be able to force its opponent to step on one of these mines. White, who is to move, can play: 77. Kg5! Ke3 78. Kg4 (zugzwang!) +-
B) In the winning variation, that is started by 65...h6!, a pair of mined squares is created, too (highlighted in red color).
If black moves to e5 first, than he loses a pawn after Kg4; but if it is white to play Kg4 first, then black wins an important tempo with the move Ke5 (zugzwang!) allowing him to reach the key square e3 just in time.
An elegant dance around the mined squares now begins:66. Kg2 Kf5 67. Kh3 Ke6! (67...Ke5? 68. Kg4! =) 68. Kh4 Kd5! (68... Ke5? 69.Kg4=) 69. Kg4 (69. Kh5 Kd4 70. Kh6: Ke3-+) 69... Ke5! (zugzwang!) 70. Kh5 Kd4 71. Kg4 Ke3 -+
Position 2:
WGM Anna Zozulia — Ralph Buss
Winterthur Chess Week 2002
Did black well to exchange minor pieces here with the moves 41... Nd1-e3+ 42. Kc4-b5 Ne3xd5 43. e4xd5 reaching a pawn ending (by the way: in the game followed 43...Kd6xd5 44. Kb5xb6 a5xb4 45.c3xb4 e5-e4 and further 21 moves that lead to a white win) ?
Solution:
Although black was not successful with it in the game, it was a good decision to exchange minor pieces.
Black's loss has not occurred due to this exchange. After the moves 41... Ne3+ 42. Kb5 Nd5: 43. ed: it was the capture 43...Kd5:? that cost the game, because after the pawn race 44.Kb6: ab: 45.cb: e4 46. a5 e3 47. a6 e2 48. a7 e1Q the white pawn promotes with a check 49. a8Q+ and as the game showed the passed pawn on b4 is just too strong.
The best continuation after the exchange of minor pieces would have been 43...e4! letting the pawn run immediately, without capturing on d5 first. After this white has two possible moves:
A) 44. Kc4?
44...b5!! Black creates a second passed pawn. 45. ab: e3 46. Kd3 a4 -+
B) 44. ba: ba: only after eliminating the possibility b5!! white can afford playing 45. Kc4. The consequence is a forced transition to a queens ending 45...e3 46. Kd3 Kd5: 47. Ke3: Kc4 48. Kd2 Kb3 49. Kd3 Ka4: 50.Kc4 Ka3 51. Kb5 a4 52. c4 Kb3 53. c5 a3 54. c6 a2 55. c7 a1Q 56. c8Q
in which black has an extra pawn and the advantage of being to move. He should have fairly good winning chances, although there are some drawing chances for white.
P.S.: Avoiding the exchange does not lead to an advantage for black, for instance: 41...Kc7 42. ab: ab: 43. Kb5 Nc3:+ 44. Ka5: Kd6 45. Bb3 =.
Position 3:
Martin Leutwyler — IM Andreas Huss
Winterthur Chess Week 2002
After the moves 53. c4-c5 b6xc5 54. b4xc5 Kg5-f5 55. Kf1-e2 Kf5-e6 56. Ke2-e3 Ke6-d5 57. c5-c6 Kd5xc6 58. Ke3xe4 Kc6-d6 white found himself in a lost position, that black eventually won.
Can you find an improvement for white?
Solution:
White could have saved himself, if instead of the move 53. c5?, that unnecessarily weakens the c-pawn, he had chosen the calmer continuation 53. Ke2. The analysis runs as follows:
53. Ke2 Kf5 54. Ke3 g5
54...Ke6 transposes to the main variation after 55.Ke4: g5 56. c5.
55. c5 bc: 56. bc: Ke6 57.Ke4:
Compared with the game, the pawn c5 now stays on the board and creates vital counter play for white, e.g.:
57... a6
After this move, black has to play carefully, too; an easier draw would be reached by 57...h4.
58. c6 h4!
Other moves lose for black, e.g. 58...Kd6 59.c7 Kc7: 60. Ke5: +-
59. gh: gh: 60. Kf3 Kd6 61. Kg4 Kc6: 62. Kh4:
Now black can win the pawn on a2 and white can pick up the pawn on e5 but the ensuing pawn race will see the pawns promote simultaneously — the game is drawn.
Position 4:
GM Normunds Miezis — GM Petr Haba
Winterthur Chess Week 2006
What is your evaluation of this pawn ending (white is to move)?
Solution:
This position clearly shows the importance of small details in pawn endings:
- if the black a-pawn would stand on a6, white would win
- if the white pawn from g2 was on h2, white would win, too,
- and if the black pawn on h5 had already moved to h4, the position would be drawn.
But all these philosophical considerations do not help white, because the position is like it is — namely lost for him. The game confirms this verdict:
41. Kd2 Ke7 42. Kd3 Kd6 43. Ke4
43. Kc4 is hopeless too after 43...h4!, when white will eventually end up in zugzwang and has to give up his d5 pawn; e.g..: 44. a3 a6! 45. a4 a5 -+.
43... h4! 44. a4 a5 (zugzwang!) 45. f5 gf:+ 46. Kf5: c4 47. Ke4 c3 48. Kd3 Kd5: 49. Kc3: Ke4 50. Kd2 Kf5 51. Ke3 Kg5: 52. Kf3 Kf5
White resigned .
