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| May-12-10 | | jsheedy: 54. Kf3, Kxb5, 55. Ke4, Kc4, 56. Bd4, b5, 57. g6, and black can't stop the g-pawn before promoting his b-pawn. Let's check.... |
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| May-12-10 | | jsheedy: awfulhangover: Only you and I tried 54. Kf3. I think it does win, but less spectacularly. I didn't use a computer. |
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May-12-10
 | | doubledrooks: A fantastic puzzle! Like others, I considered 54. Bd4, but felt that 54...Bd2 gave black excellent drawing chances. So I went back and finally found 54. Bxb6. But even after seeing this it took me awhile to evaluate all the variations. One nice line is 54. Bxb6 Bc3 55. Ba5 Be5 56. Bc7! Bxc7 57. g6 Be5 58. b6  |
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| May-12-10 | | Marmot PFL: < jsheedy> At first I thought only 54 Bxb6 would win, but now I think you are right. |
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| May-12-10 | | TheaN: <jsheedy>
You're right about that in THAT particular variation, although it's less than Bannik hoped for with mate in 23 with 54.Kf3 Kxb5 55.g6, and in practice drawing chances are pretty high for Black. However, what if Black does not play 54....Kxb5 but 54....Bc3. I'm guessing White has hardly no way to get the Black Bishop off the scope of g7, and the b-pawn will fall anyway. For instance after 54....Bc3 55.Ke4 Bg7 56.Bd4 Bh6 I think a draw cannot be avoided by White after 57....Kxb5 (which will always be possible with the White King not around). |
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| May-12-10 | | jsheedy: I finally plugged it into Rybka 2.2, set for 25 minutes, and it played 54. Bxb6, Bc3, 55. Ba5, Be5, 56. b6, Kd5, 57. b7, Ke6, 58. g6, Bd6, 59. g7, Kf7, 60. Bc3, Bf4, 61. Kf3, Bb8, 62. Ke4, Ba7, 63. Kf5, Bb8, 64. Bd4, Bd6, 65. Be5, Bc7, 66. Bxc7, Kxg7, 67. Be5+, Kf8, 68. Kf6, Kg8, 69. b8=Q+, Kh7, 70. Kf5, Kh6, 71. Qh8#. |
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| May-12-10 | | Patriot: <<Once>: But a gamble like this is preferable to being crushed like a bug as white calmly exchanges pieces then wins with the extra pawn.> Yep! This is one area where human players and chess engines disagree. When you are losing you may as well risk losing more with the prospect of equalizing or at least minimizing your opponent's winning chances. Or maybe even turn the game around completely. There is an opposite approach Dan Heisman calls the "principle of infinite resistance", which is basically about putting up your best defense with hopes that you will be able to defend or your opponent will screw up at some point. But this all depends on how badly you are losing. On move 25, I'm not sure which approach is best. |
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| May-12-10 | | YouRang: Just for laughs, I tried this position against <Little Chess Partner>. I gave it 54.Bd4, and it was smart enough to not take it, but it opted for another losing move: <54...Kd5?> (with intent to chase down the g-pawn). LCP stops the g-pawn, but now my king can run over to eat black's b-pawn and promote over there. |
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| May-12-10 | | jsheedy: TheaN: 56. Bd4?, Bxd4. Check the position again. 56...Bh6? loses to 57. gxh6. After your 55...Bg7, 56. Bxb6, Kxb5, 57. Bd4, Bf8, 58. Kf5, Kc6, 59. Ke6 seals the deal. Black is in zugzwang. |
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| May-12-10 | | jsheedy: In my last line, 58. Kd5 cuts off the black King quicker. |
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| May-12-10 | | fouard: Simple. 54 Bxb6, forcing ...Bxb6. Then 55 g6 forces ...Bd4. Now 56 b6. |
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| May-12-10 | | shuriken68: isn't this the already classical "Shirov" sacrifice? He used it once after he lost an endgame to a scandinavian GM; don't recall the games and names,unfortunately. |
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| May-12-10 | | shuriken68: ...played a half of a century earlier... |
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| May-12-10 | | rapidcitychess: <tarek> Thanks for the slightly uplifting comment. |
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| May-12-10 | | reztap: For once I saw imediately the correct move. Does not happen that frequently. |
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| May-12-10 | | TheaN: <jsheedy: TheaN: 56. Bd4?, Bxd4. Check the position again. 56...Bh6? loses to 57. gxh6. After your 55...Bg7, 56. Bxb6, Kxb5, 57. Bd4, Bf8, 58. Kf5, Kc6, 59. Ke6 seals the deal. Black is in zugzwang.> Have to admit that those two blunders are sloppy but it's the idea: the fact that White can't play 56.Bd4 seems to make it even easier, negating the use for 56....Bh6 (and if it would still be necessary 56....Bf8 is the counterpart, of course). Lets follow your variation until six pieces are left, which is after 56.Bxb6, and check Nalimov: 54.Kf3 Bc3 55.Ke4 Bg7 56.Bxb6: Mate in -19 moves from Black's perspective. Looks like you're right then. The idea that Black is forced to take the b-pawn, allowing White access to d4, is sufficient in this case. You would expect a sole Bishop to draw this, but it seems not. 54.Kf3 is a nice find then, calculating it through like this. |
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| May-12-10 | | prbprb2: Is anyone winning after Black's 50th move? Or did black play poorly beyond that? |
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| May-12-10 | | wals: Rybka 3 1-cpu: 3071mb hash: depth 15:
Black.
+1.07 22...Bb5. better Nxd5, =0.00.
+3.11 25...Nxe4.better Ne8, +1.48.
White.
+0.30 26.Qb4. better fxe4, +3.11.
Black loses the plot with-
+5.11 51...b6. better Kd5, Bd8, or
Ke5, +0.73. |
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| May-12-10 | | ZorinNighthawk: I missed this one... was thinking Bd4 ... I looked at taking the pawn. I just didn't look deep enough for either move. If it was a smothered mate i bet i would have got it. ;) |
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| May-12-10 | | Marmot PFL: <prbprb2> If black can't take b5, than 51...b6 looks very bad. 51...Kd5 52 Kxg2 Ke4 seems a much better chance. |
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| May-12-10 | | ZUGZWANG67: Bishop of the same color endgame; W's a pawn up. I think W's (only) winning plan is to sacrifice it's B for B's last pawn, being given that the BB can't stop the two W's remaining units from one and only diagonal. So: 54.Bxb6 Bxb6 (54...Kxb5 55.Bxa5 Kxa5 56.g6 1-0) 55.g6 Bd4 56.b6 (56...Bxb6 57.g7; 56...Be5 57.b7 K-moves 58.b8Q and 59.g8Q). Such a tortured (Black) bishop has been named "the pants" by Dvoretsky in his ecxellent "Dvoretsky's endgame manual", probably refering to Black tearing it's pants trying to prevent both W's pawns from promoting. Time to check...(GULP!)
***
Got it! |
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May-12-10
| | OBIT: Interesting position! For 54. g6, suggested by <rapidcitychess> a ways back, I think the main line is 54. g6 Bc3 55. Kf3! (this seems to be the only winning move) Kxb5 56. Ke4 Bg7 (if 56. Kc4 Bxb6) 57. Kd5 Ka5 58. Bd4 Ba6 (58...Bf8 59. Ke6 b5 60. Kf7 Bh6 61. Be3 saves a tempo over the main line) 59. Ke6 b5 60. Be3! (60. Kf7? b4 61. Be3 b3! 62. Bxh6 b2 63. g7 b1=Q Qa2+ draws) Bg7 61. Kf7 Bc3 62. Bg5 b4 63. Bf6 Bxf6 64. Kxf6 b3 65. g7 b2 66. g8=Q b1=Q 67. Qa8+ Kb4 68. Qb8+ and wins. Possibly there is a slight error in this analysis that makes the finale more exciting than it has to be, but that is one hair-raising finish. |
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| May-12-10 | | ZUGZWANG67: << rapidcitychess:> No smothered mate?
54.g6 seems to be the solution after... 54...Bc3 forced 55.Bxb6 Kxb5 with a winning Bishop endgame using Centuri's rule the the h6-f8 line is to short. Hard to say but that must be the solution.> This is true as far as Centurini is concerned but I think that the fact that the pawn is a Knight-pawn renders the idea unapplicable: the WK can't come in front of the pawn. I did not verify all the lines nor did I use software to support my point, but here's what I found: 56.g6 Bc3 55.Bxb6 Kxb5 (your line)56.Be3 (the best location?) Kc4 57.Kf3 Kd5 58.Kg4 Ke6 59.Kh5 (59.Kg5 blocks the B) 59...Bg7 60.Bh6 Kf6 61.Bg5+ Kf5 (diagram)
click for larger viewBut take the whole position after 59...Bg7 and move it one file to the left. We obtain the following diagram:
click for larger view
Here after 60.Kh6, W wins. That is so because first, the WK comes to g7 and second and importantly, the BK fails in reaching g5 on time in order to secure two squares for it's B, e7 being not available for that purpose. |
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| May-13-10 | | openingspecialist: http://www.shredderchess.com/online... After:
54. Bxb6 #20
best response is:
54. ... Bb4 55. Ba5 Bxa5 56. g6 Bc3 57. b6 Be5 58. b7 Kd5 59. g7 Bxg7 60. b8=Q Be5 61. Qa8+ Kd4 62. Kf3 Bd6 63. Qe4+ Kc5 64. Ke3 Bc7 65. Qf5+ Kc6 66. Kd4 Bb6+ 67. Kc4 Be3 68. Qe6+ Kc7 69. Qxe3 Kd6 70. Qe8 Kc7 71. Kc5 Kb7 72. Qd7+ Ka6 73. Qg7 Ka5 74. Qa1# |
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| Jun-18-18 | | Omnipotent00001: 53. Kf3 mates in 25 moves. |
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