I think that in order to prove a solution we need to refute every possible line that is not losing based on the computer.Marc MP wrote:Hi Karol,Karol Majewski wrote:I will play 8...a5! and after 9.c4 Qa3!JVMerlino wrote:Yep, that MIGHT hold. Not sure, but here's the continuation I see:

1.Qxe5 fxe5 2.Rf1 Qe7 3.Bd1 b5 4.Bb3 Rc4 5.Kg2 {avoiding check on c5} a6 6.Bxc4 bxc4 7.b3 cxb3 8.axb3 Qe8 9.c4 Qe7

draw!

I think you're right, and 8...a5! will draw! This more or less refutes the solution I had:

1. Qxe5 fxe5 2. Rf1 Rc8 3. Bd1 Rc4 4. Bb3 b5 5. Bxc4 bxc4 6. b4 * which is similar.

So I searched for an improvement and I think I found one!

1. Qxe5 fxe5 2. Rf1 Rc8 3. Bd1 Rc4 4. Bb3 b5 5. a4! a6 {seems forced} 6. Ba2!! Qe7 {lets try this} 7. b4! *

[D]6kr/4q2p/p3P1pB/1p2p3/PPr1P3/2P5/B6P/5RK1 b - b3 0 1

Now white will capture the c4-rook with a winning Q-side pawn structure! Pushing the b-pawn will give an easy win!

Here is Toga 1.3 X4 analysis from the diagram (score relative to Toga - black here):

And CM9_R1 (score relative to white):Code: Select all

`00:22:12.5 0,00 18 627003769 Qd8 Rf7 Qe8 Bxc4 bxc4 Rg7+ Kf8 Rc7+ Kg8 Rg7+ 00:24:38.4 -5,58 19 706926332 Qd8 Bxc4 bxc4 b5 axb5 axb5 Qb8 e7 Qa7+ b6 Qxe7 b7 Qd8 Rf8+ Qxf8... 00:29:39.8 -2,95 19 868872523 Qa7+ Kg2 Qg7 Bxg7 Kxg7 Bxc4 bxc4 Rf7+ Kh6 Rd7 Re8 e7 Kg7 b5 ... 00:35:20.8 -3,05 20 1046837979 Qa7+ Kg2 Qg7 Bxg7 Kxg7 Bxc4 bxc4 Rf7+ Kh6 Rc7 Kg5 e7 Kf6 b5 ... 00:42:52.4 -2,85 21 1296150453 Qa7+ Kg2 Qg7 Bxg7 Kxg7 Bxc4 bxc4 Rf7+ Kh6 Rc7 Kg5 e7 Kf6 b5 axb5 axb5 Ke6 b6 Kd6 Ra7 Rb8 Kf3 h6 Ke3 g5 Kf3 h5 Ke3`

I don't think black can prevent this winning set-up for white. Any comments?Code: Select all

`1:15 3/14 6.79 21533083 1...De8 2.Fxc4 bxc4 3.b5 axb5 4.axb5 Dd8 5.Rg2 Da8 6.Rg3 Da3... 3:19 3/14 2.37 54352033 1...Dd8 2.Fxc4 bxc4 3.Rg2 g5 4.b5 axb5 5.axb5 Da8 6.Rg3 Dc8 7.Tf5 ... 8:29 4/15 3.53 137867222 1...Dd8 2.Fxc4 bxc4 3.Rg2 g5 4.b5 axb5 5.axb5 Da8 6.Rg3 Dc8 7.Tf5... 22:22 4/15 3.10 351917628 1...Da7+ 2.Rg2 Dg7 3.Fxg7 Rxg7 4.Fxc4 bxc4 5.Tf7+ Rh6 6.e7 Te8... 29:23 4/15 2.83 455845961 1...Dg7 2.Fxg7 Rxg7 3.Fxc4 bxc4 4.Tf7+ Rh6 5.Rg2 Te8 6.e7 g5 7.Tf6+ Rg7 8.Txa6 Txe7 9.a5 Rf7 10.b5 Re8 11.Ta8+ Rd7`

Based on glaurung depth 21

There are 6 possible moves that we need to refute(other options lead to mate)

New game

4q1kr/p6p/1pr1P1pB/4p3/4P3/2P5/PP2B2P/5RK1 b - - 0 1

Analysis by Glaurung 1.2.1:

1. ³ (-0.51): 2...a6 3.Bxa6 Rc7 4.Bb5 Qe7 5.Kg2 Rc5 6.Ba4 b5 7.Bb3 Rc4 8.Bxc4 bxc4 9.b4 cxb3 10.Rf7 Qxf7 11.exf7+ Kxf7 12.axb3 Rd8 13.b4

2. = (-0.14): 2...Rc8 3.Bd1 Qxe6 4.Bb3 Qxb3 5.axb3 a5 6.Rf6 Rd8 7.Kf2 Re8 8.Ke3 Ra8 9.Kf3 Rc8 10.Rxb6 Kf7 11.Ra6 Rb8 12.Ra7+ Ke6 13.Ra6+ Kd7

3. = (-0.07): 2...Rc7 3.Bb5 Qe7 4.Ba4 Qc5+ 5.Kg2 Rg7 6.Bb3 Qe7 7.Kh3 g5 8.Bd5 a6 9.Bxg7 Kxg7 10.Rf7+ Qxf7 11.exf7 Rf8 12.Kg4 Kg6 13.a3 h5+ 14.Kf3

4. = (0.00): 2...Rc5 3.Bd1 b5 4.Bb3 Rc4 5.Kg2 a6 6.Kg3 Qe7 7.Kg2 Qe8 8.Kg3

5. = (0.00): 2...Qd8 3.Bd1 Qe7 4.Bb3 Rc8 5.Kg2 Re8 6.Rf7 b5 7.h4 a5 8.Bg5 Qd6 9.e7 h6 10.Rf8+ Kg7 11.Rf7+ Kg8 12.Rf8+

6. = (0.00): 2...Qe7 3.Bd1 b5 4.Bb3 Rc4 5.Kg2 a6 6.Kg3 Qe8 7.Kg2 Qe7 8.Kg3

7. +- (#13): 2...b5 3.Bxb5 Qe7 4.Bxc6 Qg5+ 5.Bxg5 h6 6.Bd5 hxg5 7.Rf7 Rh7 8.e7 Rxf7 9.e8Q+ Kg7 10.Qxf7+ Kh6 11.Qf8+ Kh5 12.Qh8+ Kg4 13.Kf2 Kf4 14.h3 g4 15.Qf6#

(Uri, MyTown 10.04.2007)