XChess1971 wrote on 02/26/10 at 02:38:22:


Hi! I'm not an expert in endings, but let us see what can happen in this ending. Black plays 29...Bc6 followed by e5 and a5 and waits (the b-pawn remains on b7) by moving his bishop between c6, e8 (and a4). White has very limited possibilities. Kd3 is always followed by Bb5+ and if c4 Bc6 c5 dxc5 Kc4 then Black plays b6 and waits with Kh8, Kg8 when White doesn't make progress. In general a c5-breakthrough is no real threat.
The only strong plan for White is to head with his king to g5. Let's say White moves his pawns to a3, c4, c3 and moves his King to g3. If Black takes the pawn on e4, then White's knight escapes to d7, which is probably sufficient for White's win. If he doesn't take on e4, then White plays Kh4, forcing a reaction from Black's side. The only thing Black really can do here is to play f6 (the same move can be played against Kg4, too. In that case Ne6 is not possible and Black will play Kf7 next). Then Ne6 and (assuming the bishop is on c6) Bxe4. It's still unclear whether Black has a draw here, but it seems that's the point where analysis should start. White's king could be on h4, g3 or f2.

EDIT: Let me add a diagram for the critical position.
(White to move)

Hi:

First of all I won't touch 16.Bh6. It doesn't seem to be testing for the variation.
After 16.Rdg1 not one single game was answered with 16...e6. The alternatives are:

a) "Main Variation: 17.Bg5!"

b)17.Bh6 Qf6 transposing to Dominguez Perez - Carlsen with an equal game.
c)17.fxg4 Nf6 18.Bg5 Re8 19.Qh2 a5 with a complex game. Maybe this could be deepened to really know the full truth comparing Khalifman's.
d)17.Nd1 g3 18.Bg5 Qe8 19.Bh6 Kh7
e)17.f4 Nc4 18.Bxc4 Rxc4 19.Rxg4 e5 20.Nf5 exf4 21.Bf2 Rxc3 22.bxc3 Nf6 23.Rxf4 Nxe4 24.Rxe4 Bxf5 with an unclear game.
f)17.Rh2 gxf3 18.Bh6 f2 19.Rxf2 Nf6 with a good position for black.
g)17.a3 gxf3 18.Nd1 Kh7 19.Nf2 Rh8 and black is doing good!.

Going back to 17.Bg5! there are different alternatives:
The "supposedly main one" 17...Qb6.

Other alternatives:
1) 17...Bf6 18.Bh6 Rxc3 (18...Bh8!?; 18...g3!?) 19.bxc3 g3 20.Rxh5 gxh5 21.Rxg3+ Kh7 22.Bxf8 Qxf8 23.f4 Qh6 24. Rg1 Be8 25.Qg2 Ng4 26.f5 with some initiative. But maybe interesting is 24...Ng6.

2)17...Nf6 18.Bh6 Bh8 19.f4! Nc4 20.Bxc4 Rxc4 21.Bxf8 Nh5 22.Nde2 Qxf8 23.Rxg4 Bg7 24.Rg5 Nf6 (supposedly the best) 25.e5 Nh7 26.Rgg1 Bc6 27.Qd3 Bxh1 28.Qxc4 Bc6 29.Nd4 dxe5 30.Nxc6 bxc6 31.fxe5 Bxe5 32.Qxc6 with better prospects for white.

3)17...Qc7 18.Bh6!

After 17...Qb6 the best line is:
18.fxg4! Nc4! 19.Bxc4 Bxd4 20.gxh5! Rxc4 21.Rg3 (21.Nd1 Rfc8! 22.hxg6 Rxc2 23.gxf7+ Kxf7 24.Rh7+ Ke8 25.Re7+ Kd8{only move} 26.Rf7+ Ke8 27.Rgf1 Rc1+{only move} 28.Qxc1 Rxc1+ 29.Kxc1 Qc5+! 30.Kb1 {only move} d5 31.Re7+ Qxe7 32.Bxe7 Kxe7 and the pair of bishops could hold.) 21...Rxc3 (21...Rfc8 22.hxg6!) 22.Rxc3 Qb4 23.hxg6 Bxc3 24.Rh8+!! Kg7 25.Bh6+! Kxh8 26.g7+ Kh7 27.gxf8+! Kg8 (27...Kh8!?) 28.Qxc3 (28.Qg2 Kh8!) Qxc3 29.bxc3 and in this position it is black's move...

The question here is can black survive this ending???.
The white knight is trapped, and the posible "breakthroughs" are e5 and c5. Engines think that this position favors white. I still have my doubts about it. But, still it is interesting for investigation. Black's plan is to keep everything closed or create a mass of black pawns as part of the counterplay. Remember bishop+knight with no pawns against bishop alone is a draw.
Maybe some ending experts such as John Nunn, Pal Benko or Karsten Muller could give us some insight here.
It took me hundreds of hours to get to this point. You evaluate for yourselves.

Albert C. Mooren
Allentown, PA - USA


bragesjo wrote on 02/25/10 at 17:15:43:

Nobody says anything I'll let you run your engines with 16...e6. Opinions are welcome.


XChess1971 wrote on 02/07/10 at 03:04:07: