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2015 CSCC April Swiss 75

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2015 CSCC April Swiss 75
White to move. Mark McGough vs Alexsand Bozhenov
Posted by Paul Anderson on May 4, 2015 Full Size|

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7 Comments

Reply Paul Anderson
5:44 AM on May 20, 2015 
Yeah, the King on f6 looks pretty ugly. When is that 7 man database coming out?
Reply DuWayne
8:57 PM on May 19, 2015 
Paul Anderson says...
Maybe f4 is the wrong choice. What if instead the King goes to g7 and tries to overwork the Bishop like this...

59. Kg7 Be3 60. g3 Bf2 61. Kxh6 Bxg3 62. Kg7 Be5+ 63. Kh7 Ke3 64. Be4 Kf4 65. Kg6 Bd4 66. h6 Bh8 67. h7 Be5 68. Kf7 Kg5 69. Kg8 Kf4 70. h8=Q




Paul,

If 4. Kg7 Ke5! 5. Kxh6 Kf6, and Black dominates on the dark squares to keep White's pawns from queening.

DuWayne
Reply Paul Anderson
3:07 AM on May 12, 2015 
Brian Rountree says...
The interesting part is why another move may fail. I came up with this line. 1.Kg7 g5, 2.Kxh7 g4, 3.Bb7 (else ...Bg8 will give White two pawn islands, anywyay, and Black's king is better placed) Bg8, 4.fxg Bxh2, and here the question is whether White's doubled pawns win. I am not sure about either line.


Doubled Pawns win. Black loses the Bishop on front Pawn at g7 and the King can never blockade the back Pawn.

57... g4 58. Bb7 Bg1 59. fxg4 Bxh2 60. g5 Be5 61. g6 Ke3 62. g7 Bxg7 63. Kxg7
Reply Paul Anderson
2:50 AM on May 12, 2015 
DuWayne Langseth says...
Paul,

You're right
...
This may be one of White's best shots:

1. Bxg6 Bg1 2. h4 Bf2 3. h5 h6 4. f4 Ke3 5. f5 Kf4 6. f6 Kg5 7. Ke6 Bd4 8. f7
Bc5
...
DuWayne


Maybe f4 is the wrong choice. What if instead the King goes to g7 and tries to overwork the Bishop like this...

59. Kg7 Be3 60. g3 Bf2 61. Kxh6 Bxg3 62. Kg7 Be5+ 63. Kh7 Ke3 64. Be4 Kf4 65. Kg6 Bd4 66. h6 Bh8 67. h7 Be5 68. Kf7 Kg5 69. Kg8 Kf4 70. h8=Q
Reply DuWayne Langseth
12:27 PM on May 5, 2015 
Paul,

You're right that 1. Bxg6 hxg6 2. Kxg6 is mate in 24 for White. The interesting variation is where Black ignores the sac and plays 1...Bg1! The point is that opposite bishops where one side has two connected extra pawns is often a draw. Consider the following variation:

1. Kg7 Bg1 2. Kxh7 Bxh2 3. Kxg6

we arrive at one of those connected pawn opposite bishop tablebase draws.

I'm not sure if the initial position is a win for White or a draw. It would take some more analysis to figure that out. This may be one of White's best shots:

1. Bxg6 Bg1 2. h4 Bf2 3. h5 h6 4. f4 Ke3 5. f5 Kf4 6. f6 Kg5 7. Ke6 Bd4 8. f7
Bc5

And it's hard to see that White can make progress. For this reason, I lean toward the initial position being drawn.

I considered the bishop sac, but I've seen bishops often draw against three connected pawns that aren't advanced, so I chose Kg7 since I wasn't sure. My choice doesn't get anywhere.

DuWayne
Reply Brian Rountree
11:07 AM on May 5, 2015 
We need a Fritz tablebase to show us the win? I'm surprised you think that little of me, Paul (joking)! lol. I figured out your answer of sacking without too much trouble, and that was my answer too.

The interesting part is why another move may fail. I came up with this line. 1.Kg7 g5, 2.Kxh7 g4, 3.Bb7 (else ...Bg8 will give White two pawn islands, anywyay, and Black's king is better placed) Bg8, 4.fxg Bxh2, and here the question is whether White's doubled pawns win. I am not sure about either line.

During the game, I wondered if Black had a draw with 2...Bg8, 3.h6 Ke5, 4.Kg6 Kf4 followed by ....Kg3, and had thought this was a way Aleksandr could have drawn. I can't see how White can play better, so I'd say this is a draw. In fact, I was very surprised that he didn't' see this OTB and blitzed out some other weird continuation instead.
Reply Paul Anderson
1:09 AM on May 5, 2015 
56.Bxg6! is the killer. If 56...hxg6, then White plays 57.Kxg6 and can announce mate in 24.

The position has become a computer-solved endgame. You can check for yourself here: http://www.shredderchess.com/online-chess/online-databases/endgam
e-database.html

Just click Input FEN and enter this: 8/8/6K1/8/3k4/4bP2/6PP/8 b - - 0 1

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